Determination of am-binding proteins and the association of adrenomedullin (am) therewith

ABSTRACT

The present invention provides methods for the isolation, identification, and purification of adrenomedullin (AM)-binding proteins. Also, provided are methods for utilizing the purified AM-binding proteins, or functional portions thereof, to diagnose, treat, and monitor AM-related diseases, for example, diseases or disorders associated with abnormally elevated AM levels. In addition, the present invention provides a newly identified complex between AM and a specific AM-binding protein 1 (AMBP-1); which has been isolated and identified herein as factor H (fH). The invention also provides AM/AMBP complexes, particularly AM/FH complexes, and antibodies specifically reactive with this complexes. Further provided are methods for identifying and purifying complexes of AM and an AM binding protein using anti-AM/fH antibodies, and methods for treating conditions such as cancer or diabetes utilizing compositions comprising these antibodies. The present invention additionally provides methods for identifying antagonists agents that inhibit the function of AM, factor H, or the AM/factor H complex. The invention also provides methods for treating conditions such as cancer or diabetes using these antagonist agents.

RELATED APPLICATION

This application is related to U.S. Provisional Application Ser. No.60/153,397 filed Sep. 10, 1999, the contents of which are hereinincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to newly developed methods for thedetection of adrenomedullin (AM)-binding proteins. The invention furtherrelates to the isolation, identification, and use of such AM-bindingproteins, and to compositions and methods including these proteins. TheAM-binding proteins can be employed in the diagnosis, treatment andmonitoring of AM-related diseases. The present invention also relates tothe isolation of AM/AM-binding protein complexes, the generation ofantibodies to these complexes, and the use of these antibodies to detectAM/AM-binding protein complexes and treat AM-related diseases. Theinvention further relates to a newly discovered complex comprising AMand a newly identified AM binding protein, human complement factor H(fH; factor H). The present invention also relates to the identificationof antagonists that dissociate the AM/fH complex or inhibit AM/fHcomplexation, and the use of such antagonists in the prevention andtreatment of diseases, including cancers and diabetes.

BACKGROUND OF THE INVENTION

Adrenomedullin (AM) is a 52 amino acid amidated peptide hormoneoriginally isolated from adrenal tumors. AM is involved in numerousphysiological activities, including vasodilation, angiogenesis,mitogenesis, and anti-microbial functions. As a result, AM actions arerelated to a wide array of disease states such as heart and pulmonarydisease, cirrhosis, cancer, diabetes, sepsis, inflammation andpreeclampsia in mammals, including humans. (See, European Patent No. 0845 036 and U.S. Ser. No. 09/011,922, filed Feb. 17, 1998 to F. Cuttittaet al.).

In clinical studies, patients with chronic congestive heart failure showelevated plasma AM, and these concentrations increase in proportion tothe severity of the heart failure along with other hormones known toaffect the progression of the disease (J. Kato et al., 1996, J. Clin.Endocrinol. Metab. 81:180-3). Similarly, patients with congenitalcyanotic heart disease show elevated plasma AM levels and increased AMuptake in pulmonary circulation (M. Yoshibayashi et al, 1999, Clin. Sci.(Colch.), 1999, 96:543-7). Patients with chronic obstructed pulmonarydisease also show significantly raised AM plasma levels (B. Cheung etal., 1997, Clin. Sci. (Colch.) 92:59-62). Accordingly, increased AM (apotent vasodilator) may function as a compensatory mechanism forhypoxaemia (Kato et al., 1996, supra; Yoshibayashi et al., 1999, supra).

Several independent clinical studies have established that patients withliver cirrhosis show elevated circulating AM, and these levels increasewith the severity of the illness (E. Fabrega et al., 1997, Am. J.Gastroenterol. 92:1901-4; C. M. Fernandez-Rodriguez et al., 1998, J.Hepatol. 29:250-6; M. Guevara et al., 1998, Gastroenterology 114:336-43;H Kojima et al., 1998, J. Hepatol. 28:840-6). As peripheralvasodilatation has been implicated in the progression of livercirrhosis, AM may directly participate in the pathogenesis of thedisease (Fabrega et al., 1997, supra; Fernandez-Rodriguez et al., 1998,supra; Guevara et al., 1998, supra; Kojima et al., 1998, supra).

Monoclonal antibodies directed to AM have been shown to inhibit tumorcell growth in a concentration-dependent manner, an effect that isreversed with the addition of exogenous AM (M. J. Miller et al., 1996,J. Biol. Chem. 271:23345-51). AM has also been found to be expressed innumerous and diverse cancer cell lines (M. J. Miller et al., 1996,supra), as well as in small and non-small cell lung carcinomas (A.Martinez et al., 1995, Endocrinology 136:4099-105). In addition, AMbinds to specific sites on human malignant melanoma cells and exogenousAM stimulates melanoma cell growth (A. Martinez et al., 1997,Endocrinology 138:5597-604). Moreover, cyclic AMP levels in tumor cellsincreases in the presence of AM (M. J. Miller et al., 1996, supra; K.Takahashi et al., 1997, Peptides 18:1117-24), indicating that AM may actas a autocrine growth factor to promote neoplastic proliferation (M. J.Miller et al., 1996, supra).

It has been demonstrated that AM inhibits insulin secretion in adose-dependent manner, while neutralizing monoclonal antibodies directedto AM increases insulin release by 5-fold; this effect was reversed bythe addition of synthetic AM (A. Martinez, 1996, Endocrinology137:2626-32). Additionally, intravenous injection of AM reduces thelevels of insulin in the bloodstream with a concomitant increase incirculating glucose (Martinez, 1996, supra). These observationsimplicate AM as an insulin regulatory factor involved in diabetes andobesity.

In clinical experiments, septic patients showed extremely elevatedplasma AM concentrations, and those with acute renal failure hadmarkedly elevated plasma AM levels during the early course of theillness; however, AM levels declined rapidly during the recovery course(Y. Hirata et al., 1996, J. Clin. Endocrinol. Metab. 81:1449-53).Similarly, patients with systemic inflammatory response syndrome,pancreatitis, traumatic shock, or severe sepsis show significantlyincreased plasma levels of AM, and these levels increased in proportionto the severity of illness (S. Ueda et al., 1999, Am. J. Respir. Crit.Care Med. 160:132-6). AM levels also correlate with sepsis markers suchas the Acute Physiology and Chronic Health Evaluation II score and thepeak multiple organ failure score, indicating that AM levels can be usedto evaluate the severity of sepsis and can serve as an early predictorof organ failure and outcome (Ueda et al., 1999, supra).

The diverse actions of AM are thought to be orchestrated by temporaland/or tissue-specific regulatory factors. The activities of severalother peptide hormones are modulated by binding proteins present inextracellular fluids. For example, one of the most well characterizedclasses/families of hormone binding proteins are the insulin-like growthfactor binding proteins (IGF-BPs). IGF-BPs can direct, enhance, or blockthe action of IGF-1 on cells by regulating the ability of IGF-1 to bindto cell surface receptors (D. R. Clemmons et al., 1998, Mol. Cell.Endocrinol. 140: 19-24).

The detection, isolation and identification of AM-binding proteins, orfamilies of such proteins, are therefore important goals for the furtherunderstanding of AM regulation and function in both normal and diseasestates in animals, including mammals, preferably humans. Such AM-bindingproteins may stabilize or destabilize AM, direct AM to specific sites,modulate AM-binding to its receptor, or otherwise interact with AM toregulate or modulate its activity and/or function. AM-binding proteinsmay thereby provide a molecular basis for the actions of AM on differenttissues, at different times, and in different illnesses and diseasestates.

Moreover, as a result of the present invention, AM-binding proteins canbe used to quantify plasma AM levels in order to diagnose and/or monitorthe presence or progression of diseases which are characterized byaltered concentrations of circulating AM. AM-binding proteins can alsobe used to prevent or treat diseases caused or exacerbated by elevatedlevels of plasma AM by administrating AM-binding proteins in dosagessufficient to bind to AM and thereby block AM activities or interactionswith other components.

SUMMARY OF THE INVENTION

The present invention provides newly developed methods for thedetection, isolation and identification of AM-binding proteins, orfunctional portions thereof, for example, in the form of functional AMpolypeptides or peptides. The present invention further providesdiagnostics and treatments that utilize the AM-binding proteins,polypeptides, or peptides. The invention also provides a newlyidentified complex of AM and an AM-binding protein identified herein ashuman complement factor H (fH; factor H), (GenBank Accession No.CAA30403). Human complement factor H has been determined to be a markerfor urinary bladder carcinomas (R. Heicappell et al., 1999, Eur. Urol.35:81-7). In accordance with the present invention, novel therapeuticswhich utilize the AM binding protein factor H, or related AM-bindingproteins or peptides, are provided for treating cancers, particularly,urinary bladder cancer.

It is an object of the present invention to provide methods of isolatingAM-binding proteins, wherein AM is conjugated with a label or marker andincubated with cellular or extracellular lysates. The label or markermay be radioactive or non-radioactive, and is preferablynon-radioactive. In accordance with the aspect of the invention relatedto non-radioactive labels or markers of AM, AM is labeled withfluorescent, chemiluminescent, or immunoreactive molecules, or epitopetags.

It is another object of the present invention to provide diagnosticreagents comprising AM-binding proteins or peptides to detect and/ormonitor levels of AM in body fluid samples, including cell and tissuelysates and extracts.

It is yet another object of the present invention to provide methods ofusing AM-binding proteins or peptides as diagnostic reagents forquantifying AM levels, particularly circulating AM levels. Such methodsare useful for disease diagnosis, for determining disease severity, andfor following the course of treatment for diseases characterized byaltered or abnormal AM levels. These diseases include heart andpulmonary diseases, liver cirrhosis, cancers, diabetes, sepsis,inflammation, and other disorders characterized by altered AM plasmaconcentrations.

It is still another object of the present invention to provide improvedquantitative assays for detecting AM in serum, utilizing a chaotropicagent, e.g., sodium thiocyanate to dissociate AM from factor H prior toserum extraction and quantitation of AM.

It is a further object of the present invention to provide quantitativeassays for detecting AM, or peptides thereof, using factor H, or relatedAM-binding polypeptides or peptides, instead of anti-AM antibodies tocapture the AM ligand.

It is also a further object of the present invention to provide kits fordetecting AM comprising AM-binding proteins, e.g., factor H, orAM-bindable peptides thereof.

It is yet a further object of the invention to provide pharmaceuticalcompositions comprising AM-binding proteins or peptides. In accordancewith the present invention, such pharmaceutical compositions are used totreat conditions caused or exacerbated by abnormal, e.g., elevated,levels of plasma AM. These conditions include liver cirrhosis, cancers,diabetes, or other disorders caused or exacerbated by elevated AM plasmaconcentrations.

It is another object of the present invention to provide a novel complexof AM and the AM-binding protein factor H. The complex is referred toherein as AM/fH.

It is also an object of the present invention to provide isolated andsubstantially purified antibodies that have specific binding affinity orimmunoreactivity with an AM/AMBP complex or fragments of the complex,preferably the AM/fH complex or fragments derived therefrom.

It is another object of the present invention to use the above saidantibodies in methods to detect the AM/AMBP complex or the AM/fH complexin vivo or in vitro or treat AM-related conditions, such as cancer ordiabetes.

It is still another object of the present invention to provide kits formeasuring concentrations of AM/AM-binding protein complex comprisinganti-AM/AMBP antibodies, particularly anti-AM/fH antibodies.

It is an additional object of the present invention to provideantagonist agents that inhibit AM, factor H, or AM/fH activity.

It is yet another object of the present invention to provide methods oftreating cancer by administering one or more antagonist agents inamounts sufficient to inhibit AM, factor H, or AM/fH activity.

It is also an object of the present invention to provide methods oftreating cancer by administering antibodies that specifically bind tothe AM/factor H in amounts sufficient to bind to the AM/factor H complexand inhibit AM/fH activity.

Further objects and advantages of the present invention will be apparentfrom the detailed description set forth below.

DESCRIPTION OF THE FIGURES

The appended figures are presented to further describe the invention andto assist in its understanding through clarification of its variousaspects.

FIG. 1 illustrates the detection of plasma-derived AM-binding protein 1(AMBP-1) binding to labeled AM. AMBP-1 has been identified herein ashuman complement factor H (factor H), based on comparative biochemicaland protein determinations and sequence information provided in publiclyavailable databases. Lane 1: AM radiolabeled with ¹²⁵iodine; Lane 2: AMlabeled with biotin; Lane 3: AM labeled with fluorescein; Lane 4: AMlabeled with dinitrophenol. The band in each lane represents the complexformed by labeled AM binding to AMBP-1 (factor H).

FIG. 2 illustrates the results of a representative competition bindingassay to assess the specificity of binding between fluorescein-labeledAM and AMBP-1 (factor H). Lane 1: no competitor added; Lane 2: AM added;Lane 3: insulin-like growth factor (IGF-1) added; Lane 4:proadrenomedullin N-terminal 20 peptide (PAMP) added; Lane 5: insulinadded. “f-AM+” indicates fluorescein-labeled AM. The band represents theAM/AMBP-1 (AM/fH) complex that is unaffected by the presence ofcompetitor peptides.

FIG. 3 illustrates the results of a representative competition bindingassay to assess the specificity of binding between fluorescein-labeledAM and AMBP-1 (factor H). Lane 1: no competitor added; Lane 2:full-length AM added; Lane 3: AM₁₋₁₂ added; Lane 4: AM₁₆₋₂₁ added; Lane5: AM₂₂₋₅₂ added; Lane 6: AM₁₃₋₅₂ added; Lane 7: AM₃₄₋₅₂ added; Lane 8:calcitonin gene-related peptides (CGRP) added; Lane 9: amylin peptidesadded. “f-AM+” indicates fluorescein-labeled AM. The band represents theAM/AMBP-1 (factor H) complex that is unaffected by presence ofcompetitor peptides.

FIG. 4 illustrates the isolation of AMBP-1. FIG. 4A shows fractionationof human plasma by reverse phase HPLC. The dotted line indicates theacetonitrile gradient. FIG. 4B shows Coomassie Blue staining of HPLCfractions 47-51. FIG. 4C shows ligand blotting of HPLC fractions 47-51.

FIG. 5 illustrates the biochemical characterization of AMBP-1 as humancomplement factor H. FIG. 5A shows Coomassie Blue and glycoproteinstaining (GelCode Glycoprotein Staining Kit, Pierce, Rockford, Ill.) ofsamples separated by SDS-PAGE. Lane 1: horseradish peroxidase (5 μg), aglycosylated protein used as positive control; Lane 2: soybean trypsininhibitor (5 μg), a non-glycosylated protein used as negative control;Lane 3: AMBP-1 (2 μg). FIG. 5B shows Coomassie Blue staining of samplesseparated by electrophoresis on a isoelectric focusing gel pH 3-10(Novex, San Diego, Calif.). Lane 1: isoelectric focusing markers; Lane2: AMBP-1 (4 μg). FIG. 5C shows Western blot analysis of samples with ananti-factor H antibody. Lane 1: AMBP-1 (100 ng); Lane 2: AMBP-1 (200ng); Lane 3: commercially available human factor H (50 ng); Lane 4:human plasma (0.2 μl). FIG. 5D shows non-radioactive ligand blotting of1 μg AMBP-1 (Lane 1) and factor H (Lane 2). FIG. 5E shows ligandblotting of AMBP-1 (250 ng) under unreduced (Lane 1) or reducedconditions (Lane 2). FIG. 5F shows binding of fluorescein-labeled AM (50nM) to a multi-well plate coated with factor H (5 ng/well) iscompetitively inhibited by increasing concentrations of unlabeled AM(•). In contrast, AM binding to factor H is not affected by PAMP (*) orCGRP (∘). Results represent one of two independent experiments. Valuesrepresent mean and standard deviation of three determinations. “B/B₀”indicates the ratio of signals generated in the presence/absence ofunlabeled competitor.

FIG. 6 illustrates the dissociation of the AM/fH complex. FIG. 6A:Purified AMBP-1 (fraction #48) was separated by electrophoresis andtransferred to a membrane. After incubation with fluorescein-labeled AMand prior to the final development, the membrane was incubated undervarious conditions (neutral pH unless indicated). Lane 1: PBS; Lane 2:pH 11.5; Lane 3: pH 2.5; Lane 4: 4M NaCl; Lane 5: 4M NaCl pH 11.5; Lane6: 4M NaCl pH 2.5; Lane 7: 1% SDS; Lane 8: 3M Urea; Lane 9: 3MGuanidine-HCl; Lane 10: 3M sodium thiocyanate (NaSCN); Lane 11: 50%ethylene glycol pH 11.5; Lane 12: 50% ethylene glycol; Lane 13: 1%(β-mercaptoethanol. The band represents the AM/fH complex that remainsunaffected by the incubation conditions. FIG. 6B shows dissociation ofthe AM/fH complex in a multi-well plate assay system. Factor H coatedwells were incubated with fluorescein-labeled AM, and prior to thedevelopment of the assay, wells were incubated in PBS with 3M NaSCN pH7.4 for various time periods. Values represent the mean and standarddeviation of six determinations. B/B₀ represents the percentage of totalbinding.

FIG. 7 illustrates Western blot analysis of factor H and AM after C18extraction. FIG. 7A shows human plasma (1 ml) processed with a Sep PakC18 cartridge and analyzed by Western blotting with anti-factor Hantibodies. Lane 1: commercially available human factor H (10 ng); Lane2: whole human serum (0.5 μl); Lane 3: unbound fraction (1 μl). Lane 4,bound fraction (1 μl). FIG. 7B shows human plasma (1 ml) processed witha Sep Pak C18 cartridge and analyzed by Western blotting followingimmunoprecipitation with anti-AM antibodies. Lane 1: synthetic AM (1ng); Lane 2: fraction immunoprecipitated with normal rabbit serum (30μl); Lane 3: fraction immunoprecipitated with rabbit anti-AM antibody(30 μl).

FIG. 8 illustrates competitive binding curves generated by human plasmain the AM radioimmunoassay. The dilution curves of plasma (4 ml)extracted following the standard protocol (+) or the NaSCN modification(•) were compared with the standard curve of synthetic AM (∘). B/B₀represents the ratio of radioactivity bound to that bound in the absenceof added standard. The scale bar over the curves represents thedifferent plasma dilutions.

FIG. 9 illustrates the effect of factor H on AM activity. FIG. 9A showsthe effect of factor H in AM mediated cAMP induction. Cyclic AMP wasmeasured after incubating Rat-2 cells with AM and increasingconcentrations of factor H. Incubations with AM and 100 or 200 nM factorH produced a significant increase in cAMP as compared to the levelsobtained with AM alone (p<0.01** and p<0.001***, respectively).Incubation with factor H alone did not affect cAMP levels. Valuesrepresent mean and standard deviation of four independentdeterminations. FIG. 9B shows the antimicrobial effect of AM (•), factorH (*), or AM in the presence of 50 μg/ml of factor H (∘). Results areexpressed in inhibition units (10 units correspond to 1 mm of diameterin the inhibition halo). MIC values were estimated by performing alinear regression and determining the x-intercepts. The MIC value for AMwas 18.4±1.3 μg/ml, and increased to 35.4±1.1 μg/ml upon the addition offactor H (p<0.001). Values represent mean and standard deviation of themean of eight determinations.

FIG. 10 illustrates the effect of AM on factor H activity. C3b (104 kDaα′ chain and 71 kDa β chain) was incubated 24 hr at 37° C. with factorH, factor I, and various peptides. Cleavage of the C3b α′ chain producedthree bands with molecular weights 68 kD, 43 kD, and 42 kD.

FIG. 10A shows the effect of various AM concentrations on the cofactoractivity of factor H. FIG. 10B shows the effect of AM on factor Hactivity compared to the effect of the structurally related peptide CGRPand the gene-related peptide PAMP on factor H. Each figure shows arepresentative example of three different experiments.

FIG. 11 illustrates Northern blot analysis of factor H (4.3 kb) andfactor H-like (FHL-1, 1.8 kb) message expression in human tumor celllines. FIG. 11A shows the results of Northern blot analysis using thefactor H probe. FIG. 11B shows ethidium bromide staining to show theamount of total RNA loaded in each well. “CA” indicates carcinoma; “BAC”indicates bronchiolaolveolar carcinoma; “vSCLC” indicates variant smallcell lung cancer; “Adeno CA” indicates adenocarcinoma; “Squamous CA”indicates squamous cell carcinoma.

FIG. 12 illustrates immunohistochemical labeling of factor H in ratpancreas. Anti-factor H antibodies localized factor H to cells in theislets of Langerhans (FIG. 12A). This localization showed a granularpattern at higher magnification (FIG. 12B). Anti-factor H antibodiesalso localized factor H to some exocrine acini (FIG. 12C). Affinitypurified anti-factor H antibodies showed the same pattern of staining(FIG. 12D). Arrows indicate regions of factor H localization.

FIG. 13 illustrates immunofluorescence labeling of insulin (FIGS. 13A,13E, and 131), factor H (FIGS. 13B, 13F, and 13J), and either glucagon(FIG. 13C), somatostatin (FIG. 13G), or pancreatic peptide (FIG. 13K) inrat pancreas. The fourth column (FIGS. 13D, 13H, and 13L) represents ancomposite of the triple label. In all cases factor H (FH) colocalizeswith insulin (INS) in the central β cells, and factor H is absent fromthe peripheral cells which produce somatostatin (SST), glucagon (GLUC),or pancreatic polypeptide (PP). Samples were analyzed by confocalmicroscopy.

FIG. 14 illustrates immunogold labeling of factor H (small goldparticles, 10 nm in diameter) and insulin (large particles, 20 nm) inrat pancreas. Low magnification images (FIG. 14A) show that factor H islocalized to the characteristic secretory granules of the β cells, andfactor H is absent from the surrounding endocrine cell types. Highmagnification images (FIG. 14B) show that factor H is predominantlylocalized to the lucent haloes, and insulin is predominantly localizedto the dense granule cores. In addition, factor H is present in thesecretory granules of some exocrine cells (FIG. 14C). Samples wereanalyzed by electron microscopy.

FIG. 15 illustrates RT-PCR analysis to determine factor H expression inmouse liver and pancreas. FIG. 15A shows the factor H PCR product (839bp) amplified from mouse liver and pancreas cells. The PCR product wassequenced to determine that it contained mouse factor H sequence. RT-PCRresults were confirmed by Southern blot analysis (FIG. 15B).

FIG. 16 illustrates the effect of factor H on insulin secretion.Incubated of islets with AM and/or factor H resulted in dose-dependentdecreases in insulin secretion (FIG. 16A) and concomitant elevations oncAMP in the (FIG. 16B). A representative experiment is shown. Values foreach treatment represent the mean and standard deviation of threeindependent wells. Insulin release is expressed as the ratio between thecontents in the high glucose medium divided by the amount in the lowglucose one to allow for variations in the number of secreting cellsand/or their secretory efficiency. All values were statisticallydifferent (p<0.05) from the negative controls (first bar).

FIG. 17 illustrates the AM-binding proteins in various species detectedby ligand blot analysis using ¹²⁵I labeled human AM. The bands represent120 kD or 140 kD moieties identified in the plasma or serum of the tenspecies analyzed.

FIG. 18 illustrates decreased levels of AM-binding proteins observed inthe plasma of parasitized calves as compared to the plasma of healthycalves. The mean intensity of the bands was decreased by 67% (P<0.03).

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of the present invention encompasses a ligand blottingassay in which AM as ligand is labeled with a radioactive ornon-radioactive molecule, marker, or tag, and used as a probe toidentify an AM-binding protein or an AM-binding fragment thereof.Preferred in the present invention are non-radioactively labeled AMligands.

Labeling of AM

Numerous methods may be used for the non-radioactive labeling of AM orrelated peptides. For example, coupling agents such as aldehydes,carbodiimides, dimaleimides, iminodiacetates, succinimides,aminobenzamidines and related compounds can be used to conjugate AMpeptides with fluorescent, chemiluminescent, or chemical labels.Examples of nonradioactive labels that can be used include, but are notlimited to, fluorescent labels such as fluorescein and its derivatives,e.g., fluorescein isothiocyanate, rhodamine and its derivatives, dansyl,and umbelliferone; chemiluminescers such as2,3-dihydrophthalazine-dione, and chemical groups such as dinitrophenol(DNP), digoxigenin, and biotin.

AM or peptides derived therefrom can also be tagged with amino acidsequences that carry immunoreactive epitopes. A non-limiting list ofsuitable epitope tags includes c-myc, haemagglutinin (HA), polyhistidine(6X-HIS), GLU-GLU, and DYKDDDDK (FLAG®) tags. Epitope tags can be addedto polypeptides or peptides by a number of established methods. The DNAsequences of epitope tags can be inserted into polypeptide or peptidecoding sequences as oligonucleotides or via primers used in PCRamplification. Alternately, polypeptide or peptide coding sequences canbe cloned into specific vectors that create fusions with epitope tags;for example, pRSET vectors (Invitrogen Corp., San Diego, Calif.).

The complete AM peptide, or fragments derived from AM, preferably havingthe same or equivalent function as AM, can be used. AM peptides that maybe useful have been described in patent application U.S. Ser. No.09/011,922, filed Feb. 17, 1998 to F. Cuttitta et al.

In another aspect of the present invention, AM can be tagged or markedwith radioactive isotopes, such as ¹²⁵I, ¹³⁵I, ³⁵S, ¹⁴C, or[³H]-thymidine, as nonlimiting examples. Those having skill in the artknow how to label proteins and peptides with radioactive isotopic labelsusing methods and protocols routinely practiced in the art. For example,AM can be labeled by incorporating ¹⁴C or ³⁵S labeled amino acids duringprotein synthesis in host cells or cell-free expression systems (seebelow). This radiolabeled AM can then be isolated and assayed for itsbinding to the AM-receptor to confirm its biological function.

Identification of AM-Binding Proteins

Candidate AM-binding proteins, polypeptides, or peptides derivedtherefrom, can be identified and analyzed by many well-known methods inthe art (see T. E. Creighton, Ed., 1997, Proteins Structure: A PracticalApproach, IRL Press at Oxford Press, Oxford, England). As used herein,the terms protein and polypeptide are synonymous. Peptides are definedas fragments or portions of proteins or polypeptides, preferablyfragments or portions having the same or equivalent function or activityas the complete protein.

AM-binding proteins can be obtained from biological samples, such asplasma and body fluid samples of animals, including cells and tissuesand lysates or extracts derived therefrom. Suitable animal sources ofAM-binding proteins include birds, fish, insects, and mammals, includinghumans. The proteins obtained from these sources can be separated intobands by size fractionation using sodium dodecylsulfate-polyacrylamidegel electrophoresis (SDS-PAGE) and transferred by electroblotting, forexample, onto a suitable solid-phase matrix, support, or membrane (e.g.,glass or polymer beads or nylon reinforced nitrocellulose orpolyvinylidene fluoride). The support can then be incubated with labeledAM. Proteins/polypeptides that correspond to bands that exhibit specificbinding with labeled AM are then identified, isolated/purified, andanalyzed by amino acid analysis and Edman degradation to determine theamino acid sequence of peptides derived therefrom.

Sequences determined from Edman degradation can be compared with subjectsequences in available databases such as, without limitation, GenBank,SwissProt, BLOCKS, and Pima II. These databases, which containpreviously identified and annotated sequences, may be searched for thefull-length polypeptide and gene sequence using, for example, BasicLocal Alignment Search Tool (BLAST; S. F. Altschul, 1993, J. Mol. Evol.36:290-300; S. F. Altschul et al., 1990, J. Mol. Biol. 215:403-10).

In cases where the full-length sequences of AM-binding proteins are notavailable, extended or overlapping partial clones may be obtained bytechniques conventionally known and practiced in the art. Non-limitingexamples of such techniques include hybridization to plasmid or phagelibraries of genomic DNA or cDNA; PCR from the same libraries usingAM-binding protein primer pairs; or hybridization or PCR directly togenomic DNA or cDNA. These clones may then be sequenced and assembledinto full-length genes using the fragment sequence alignment program(PHRAP; Nickerson et al., 1997, Nucleic Acids Res. 25:2745-2751).

Purification of AM-Binding Proteins

Isolated AM-binding proteins or peptides may be used in diagnostics andtreatments according to the present invention. An isolated protein orpeptide as used herein refers to a component that is removed from itsoriginal environment (for example, its natural environment if it isnaturally occurring). An isolated protein or peptide contains less thanabout 50%, preferably less than about 25%, and most preferably less thanabout 10%, of the components with which it was originally associated.Preferably, an isolated polypeptide or peptide is at least about 80-90%pure, more preferably at least about 90-100% pure.

Both naturally occurring and recombinant forms of the AM-bindingproteins or peptides can be used. Methods for directly isolating andpurifying polypeptides from natural sources such as cellular orextracellular lysates are well-known in the art (see E. L. V. Harris andS. Angal, Eds., 1989, Protein Purification Methods: A PracticalApproach, IRL Press, Oxford, England). Such methods include, withoutlimitation, preparative disc-gel electrophoresis, isoelectric focusing,high-performance liquid chromatography (HPLC), reversed-phase HPLC, gelfiltration, ion exchange and partition chromatography, andcountercurrent distribution, and combinations thereof. Naturallyoccurring polypeptides can be purified from many possible sources, forexample, plasma, body cells and tissues, or body fluids.

To produce recombinant AM-binding proteins or peptides, DNA sequencesencoding the AM-binding proteins or peptides are cloned into a suitablevector for expression in intact host cells or in cell-free translationsystems (see J. Sambrook et al., 1989, Molecular Cloning: A LaboratoryManual, 2^(nd) Edition, Cold Spring Harbor Press, Cold Spring Harbor,N.Y.). Prokaryotic and eukaryotic vectors and host cells may beemployed. The particular choice of vector/host/translation system is notcritical to the practice of the invention. DNA sequences can beoptimized, if desired, for more efficient expression in a given hostorganism. For example, codons can be altered to conform to the preferredcodon usage in a given host cell or cell-free translation system usingtechniques routinely practiced in the art.

Cloning vectors include, but are not limited to pUC, pBluescript(Stratagene, La Jolla, Calif.), pET (Novagen, Inc., Madison, Wis.) andpREP (Invitrogen Corp.) plasmids. Vectors can contain one or morereplication and inheritance systems for cloning or expression, one ormore markers for selection in the host, e.g. antibiotic resistance, andone or more expression cassettes. The inserted coding sequences can besynthesized by standard methods, isolated from natural sources, orprepared as hybrids. Ligation of the coding sequences to transcriptionalregulatory elements (e.g., promoters, enhancers, and/or insulators)and/or to other amino acid encoding sequences can be carried out usingestablished methods.

For some purposes, it may be preferable to produce peptides orpolypeptides in a recombinant system wherein the peptides orpolypeptides carry additional sequence tags to facilitate purification.Such markers include epitope tags (described above) and protein tags,for example, glutathione-S-transferase (GST), green fluorescent protein(GFP), and maltose binding protein (MBP). Protein tags are attached topeptides or polypeptides by several well-known methods. As anon-limiting example, the coding sequence of a polypeptide or peptidecan be cloned into a vector that creates a fusion between thepolypeptide or peptide and a protein tag of interest. Suitable vectorsinclude, without limitation, the exemplary plasmids, pGEX (AmershamPharmacia Biotech, Inc., Piscataway, N.J.), pEGFP (CLONETECHLaboratories, Inc., Palo Alto, Calif.), and pMAL™ (New England BioLabs,Inc., Beverly, Mass.). The tagged polypeptide or peptide can then bepurified from a crude lysate of the translation system or host cell bychromatography on an appropriate solid-phase matrix.

Suitable cell-free expression systems for use in accordance with thepresent invention include rabbit reticulocyte lysate, wheat germextract, canine pancreatic microsomal membranes, E. coli S30 extract,and coupled transcription/translation systems (Promega Corp., Madison,Wis.). These systems allow the expression of recombinant polypeptides orpeptides upon the addition of cloning vectors, DNA fragments, or RNAsequences containing coding regions and appropriate promoter elements.

Host cells for recombinant cloning vectors include bacterial,archebacterial, fungal, plant, insect and animal cells, especiallymammalian cells. Of particular interest are E. coli, Bacillus subtilis,Staphylococcus aureus, Saccharomyces cerevisiae, Schizosaccharomycespombe, Neurospora crassa, SF9, C129, 293, NIH 3T3, CHO, COS, and HeLacells. Such cells can be transformed, transfected, or transduced, asappropriate, by any suitable method including electroporation, CaCl₂—,LiCl—, LiAc/PEG-, spheroplasting-, Ca-Phosphate, DEAE-dextran,liposome-mediated DNA uptake, injection, microinjection, microprojectilebombardment, or other established methods.

Antibody-based methods may also be used to purify natural orrecombinantly produced AM-binding proteins or peptides. Antibodies thatrecognize these polypeptides, or peptides derived therefrom, can beproduced and isolated using methods known and practiced in the art.AM-binding polypeptides or peptides can then be purified from a crudelysate by chromatography on antibody-conjugated solid-phase matrices(see E. Harlow and D. Lane, 1999, Using Antibodies: A Laboratory Manual,Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.). Otherpurification methods known and used in the art may also be employed.

The AM-Binding Protein Human Complement Factor H (fH)

In a preferred embodiment of the present invention, the AM-bindingprotein is human complement factor H. Factor H was originally identifiedas an important modulator of the complement cascade of the immune system(see M. P. Dierich, 1988, Mol. Immunol. 25:1043-51). Specifically,factor H forms a complex with factor I, and the fH-fI complexselectively degrades C3b, inactivates the C3 convertase, and competesfor factor B binding to C3b (P. F. Zipfel, et al., 1999,Immunopharmacol. 42:53-60). In addition, factor H can bind to theintegrin receptor (CD11b/CD18) expressed in a variety of human tissues,and bind to certain surface glycosaminoglycans present on bothprokaryotic and eukaryotic cells (P. F. Zipfel, et al., 1999,Immunopharmacol. 42:53-60).

The full length cDNA (4.3 kb) for human factor H has been cloned andsequenced and found to undergo alternative gene splicing to give rise toa shorter message (1.8 kb) (P. F. Zipfel et al., 1999, Mol. Immunol.36:241-8). This smaller message is translated into a truncated factor Hmolecule (43 kDa), denoted as factor. H-like protein (FHL-1), thatshares the complement regulatory functions of factor H (P. F. Zipfel etal., 1999, Mol. Immunol. 36:241-8). Structurally, factor H containstwenty short consensus repeats (SCRs), while FHL-1 contains seven SCRs.According to conventional nomenclature, factor H is represented as SCR1-20 with FHL-1 being SCR 1-7 (P. F. Zipfel, et al., 1999,Immunopharmacol. 42:53-60). Notably, both factor H and factor H-likeproteins have been used as markers for urinary bladder carcinomas (R.Heicappell et al., 1999, Eur. Urol. 35:81-7).

In accordance with the AM-binding protein isolation and identificationmethods described herein, the present inventors have demonstrated thatfactor H is an AM-binding protein isolated from human plasma.Specifically, a non-radioactive ligand blotting technique (Examples 1and 2; FIG. 1) and HPLC/SDS-PAGE (Example 4; FIGS. 4A-4C) purificationtechniques allowed the isolation of the AMBP-1 protein. The purifiedprotein was subjected to total amino acid analysis, N-terminal aminoacid sequence, and mass spectrometry (Example 5; Table 1). In addition,purified AMBP-1 was compared with factor H, based on apparent molecularweight, glycosylation, AM-binding, and recognition by anti-factor Hantibodies (Example 6; FIGS. 5A, 5C, and 5D). The results identifiedAMBP-1 as human complement factor H.

Additional experiments as described hereinbelow were conducted tocharacterize the AM/fH interaction (Example 7). These experiments showedthat the AM/fH complex was not dissociated in acidic or high saltconditions (FIG. 6A). In contrast, the AM/fH complex was dissociated inthe presence of chaotropic agents, such as NaSCN (FIG. 6A). Thedissociation of the AM/fH complex by NaSCN was confirmed using amulti-well AM-binding assay, 96-well plate (Example 7). The displacementcurve suggested the presence of two dissociation mechanisms, as shown byan initial rapid dissociation phase, followed by a slower dissociationphase (FIG. 6B).

Notably, the experiments described herein have shown that the AM/fHinteraction interferes with the established methodology forquantification of circulating AM (Example 8). Thus, the routineradioimmunoassay (RIA) quantification of AM fails to account for theamount of AM bound to its binding protein, factor H. The inventors'studies have indicated that the standard C18 reverse-phase separationtechnique used to prepare plasma for RIA analysis effectively eliminatesAMBP-1 (factor H) from the extract (T. H. Elsasser et al., 1999,Endocrinology 140:4908-4911; FIG. 7A). Further studies have demonstratedthat AM is detected in both the unbound and the bound fractionsfollowing C18 reverse-phase separation (FIG. 7B), confirming that thetraditional procedure does not recover the total amount of AM present inplasma. In addition, the inventors have performed a modified RIAanalysis utilizing plasma pre-treated with a chaotropic agent, NaSCN, todissociate AM/fH complexes in the plasma prior to extraction. Themodified protocol detected AM levels that were twofold higher than thoseobtained with the standard technique (FIG. 8).

The inventors' experiments have further shown that factor H modulates AMactivity, and AM modulates factor H activity. In particular, factor Henhances AM-mediated induction of cAMP in fibroblasts (Example 9; FIG.9A), but suppresses the bactericidal activity of AM against E. coli(Example 9; FIG. 9B). Additionally, AM enhances fH/fI-mediated cleavageof C3b (Example 9; FIGS. 10A and 10B). Thus, the interaction of AM andfactor H produces wide-ranging effects on both AM and factor H function.

In addition, experiments described in detail herein have shown thatfactor H and FHL-1 are highly expressed in non-small cell lung cancercells, adenocarcinoma cells, and squamous cell carcinoma (Example 10;FIG. 11). Factor H and FHL-1 are also expressed in other solid tumorcells, such as breast, colon, ovary, and prostate carcinoma cells (FIG.11). These results are consistent with recent findings, which havedetermined that factor H is expressed in a variety of human cancer cells(i.e., bladder cancer, breast cancer, and glioblastoma cells), andfactor H facilitates cancer cells' resistance to complement-mediatedcell lysis (N. S. Fedarko et al., 2000, J. Biol. Chem. 275:16666-16672;S. Junnikkala et al., 2000, J. Immunol. 164: 6075-6081; P. F. Zipfel etal., 1999, Mol. Immunol. 36:241-8).

Similarly, the inventors' studies have shown AM is expressed in severalcancer cell lines, and monoclonal antibodies directed to AM inhibittumor or cancer cell growth in a concentration-dependent manner(Martinez et al., 1995, supra; M. Garayoa et al., 2000, Mol. Endocrinol.14(6):848-862; Martinez et al., 1997, supra; Miller et al., 1996,supra). Moreover, the experiments described herein show that AMpotentiates fH/fI-mediated degradation of C3b (Example 9; FIGS. 10A and10B). The sum of these observations indicates that the AM/fH complex maymediate cancer cells' resistance to complement-mediated cell lysis.Accordingly, antagonists that inhibit AM activity, inhibit factor Hactivity, or prevent the interaction of AM and factor H may act todecrease cancer cells' resistance to cell lysis. Such antagonist agentsmay thereby be used as cancer therapeutics.

In a separate set of experiments described hereinbelow, the inventorshave used immunohistochemical labeling (Example 11; FIGS. 12A-12D) andmultiple immunofluorescence labeling followed by confocal microscopy(Example 12; FIGS. 13B, 13F, and 13J) to demonstrate that factor H isexpressed by the β cells of rat pancreatic islets. Double immunogoldstaining under the electron microscope also showed colocalization ofinsulin and factor H within the same secretory granules (Example 13;FIG. 14B). Factor H was localized to electron-lucent haloes, whereasinsulin was localized predominantly to electron-dense cores (FIG. 14B).The presence of factor H mRNA in the pancreas was confirmed by RT-PCRanalysis (Example 14; FIG. 15A).

The inventors have previously determined that AM acts to reduce insulinsecretion in the pancreas (A. Martinez, 1996, Endocrinology137:2626-32). Thus, insulin secretion assays described herein have beenused to investigate the role of factor H in pancreatic function (Example15). Such assays have demonstrated that in the presence of AM, factor Hinduces a further reduction in insulin secretion with a concomitantelevation of cAMP (FIGS. 16A and 16B). Thus, antagonists that inhibit AMactivity, inhibit factor H activity, or prevent the interaction of AMand factor H may act to increase insulin production. Such antagonistagents may thereby be used as therapeutics for conditions associatedwith reduced secretion of insulin (e.g., certain forms of type 2diabetes and pheochromocytoma).

As indicated above, factor H can act to suppress complement-mediatedcell lysis. In particular, factor H has been shown facilitate theresistance of bacterial cells (C. Neeleman et al., 1999, Infect. Immun.67:4517-4524) and tumor cells (N. S. Fedarko et al., 2000, J. Biol.Chem. (in press)) to complement-mediated lysis. It is therefore possiblethat factor H normally protects β cells from complement-mediated lysis,and inhibition or reduced expression of factor H in β cells results inthe autoimmune destruction of the cells. It is further possible that AMassists factor H in providing β cells with protection againstcomplement-mediated lysis (see FIGS. 10A and 10B). In this way, factorH, the AM/fH complex, or functional fragments thereof may be used totreat conditions associated with autoimmune responses against β cells(e.g., type 1 diabetes).

The inventors have further demonstrated that plasma proteins fromseveral species can specifically bind AM (T. H. Elsasser et al., 1999,Endocrinology 140:4908-4911; Example 16; FIG. 17). These AM-bindingproteins have been identified by a radioligand blotting techniqueadapted from P. Hossenlopp et al. (1986, Anal. Biochem. 154:138-143). AnAM-binding protein of molecular weight (M_(r)) 120 kD (undernon-reducing conditions) has been observed in the plasma from most ofthe species analyzed, including humans. It is noted that the human 120kD AM-binding protein corresponds to AMBP-1 (factor H), described indetail herein. Interestingly, an additional band of M_(r) 140 kD hasbeen observed in the plasma from ruminant species (i.e., calf, goat, andsheep). This band may represent a different protein or a differentglycosylation pattern of the 120 kD protein. From these experiments, itis concluded that AM-binding proteins in animal and avian species mayinteract with AM to form AM/AMBP complexes similar to the AM/fH complexdescribed herein.

Antibodies to AM-Binding Proteins

The present invention provides antibodies that specifically recognizeAM/AMBP complexes or fragments of these complexes, preferably AM/fHcomplexes or fragments derived therefrom. The present invention alsoprovides assay methods comprising these antibodies to identify and/ordistinguish among AM/AMBP complexes, preferably the AM/fH complex, invivo or in vitro. For example, the methods involve the use of theantibodies, or labeled antibodies, that have been bound to a solidsupport or matrix in assays, e.g., immunoassays, to bind to the AM/AMBPcomplex, or a complex-specific fragment thereof.

In accordance with the invention, specific antibodies can be generatedthat recognize and bind to a specific complex of AM and an AM-bindingprotein to aid in the identification and detection or isolation of thecomplex. Preferred are antibodies that recognize and bind to the AM/fHcomplex, but do not recognize and bind to either AM or factor H alone.One method for utilizing the antibodies according to the presentinvention to isolate AM/AM binding protein complexes in a biologicalsample comprises providing a solid support to which are bound antibodiesthat recognize a specific AM/AM binding protein complex, or acomplex-specific fragment thereof, contacting the support with thesample or an aliquot of the sample and eluting the complex that binds tothe antibodies adsorbed onto the support. Another method for detectingAM/AM binding protein complexes in a sample comprises incubating thesample with antibodies that specifically recognize and bind to a complexof AM and an AM binding protein, or a complex specific fragment, underconditions that allow the antibodies to bind to the AM/AM bindingprotein complex and determining the binding of the antibodies to thecomplex.

As used herein, “antibody” refers to intact molecules as well asfragments thereof, such as Fab, F(ab)₂, and Fv, which are capable ofbinding an epitopic determinant. Antibodies that bind to the AM/AMBPcomplex, preferably AM/fH, can be prepared using the isolated AM/AMBPcomplex, preferably, AM/fH, or fragments containing small peptidesspecific to the complex as the immunogen or immunizing antigen.Antibodies can also be generated to AM-binding proteins or fragmentsderived therefrom using the isolated AM-binding protein or a derivedfragment, as an immunogen. As will be appreciated by those having skillin the art, the immunogen can be conjugated to a carrier protein, ifdesired, to increase immunogenicity, particularly, if a small peptide isused. Commonly used carriers that are routinely used chemically coupledto peptides include serum albumins, i.e., bovine, sheep, goat, or fishserum albumin, thyroglobulin, and keyhole limpet hemocyanin. The coupledimmunogen-carrier is then used to immunize a recipient animal (e.g.,mouse, rat, sheep, goat, or rabbit).

The term “antigenic determinant” refers to that fragment of a molecule(i.e., an epitope) that makes contact with a particular antibody. Whenthe AM/AMBP complex is used to immunize a host animal, numerous regionsof the complex may induce the production of antibodies which bindspecifically to a given region or three-dimensional structure on thecomplex; these regions or structures are referred to as antigenicdeterminants or epitopes. An antigenic determinant may compete with theintact antigen (i.e., the immunogen used to elicit the immune response)for binding to an antibody. Preferred are those antigenic determinantsthat are specific for the AM/AMBP complex.

AM/AMBP complex-specific antibodies according to the present inventioninclude polyclonal and monoclonal antibodies. The antibodies can beelicited in an animal host by immunization with AM/AMBP complex-derivedimmunogenic components or can be formed by in vitro immunization(sensitization) of immune cells. The immunogenic components used asimmunogens to elicit the production of antibodies can be isolated fromplasma, recombinantly produced, or chemically synthesized. Theantibodies can also be produced in recombinant systems programmed withappropriate antibody-encoding DNA. Alternatively, the antibodies can beconstructed by biochemical reconstitution of purified heavy and lightchains. The antibodies include hybrid antibodies, chimeric antibodies,humanized antibodies (see, for example, U.S. Pat. No. 5,585,089) andunivalent antibodies. Also included are Fab fragments, Fab′ and F(ab)₂fragments of antibodies.

AM/AMBP complex as immunogens can be obtained using techniques asdescribed above. For example, AM/AMBP complexes can be isolated andpurified by excising the complexes from gels, particularly SDS-PAGEgels. Alternatively, recombinant AM and AM-binding proteins or relatedfragments can be co-expressed in a host cell or cell-free expressionsystem and co-purified.

The immunogenic components of the AM/AM binding protein complexaccording to the invention are useful as antigens for preparingantibodies by standard methods. These antibodies, whether polyclonal ormonoclonal, can be used, for example in an immobilized form bound to asolid support by well-known methods, to purify the immunogeniccomponents, specifically, AM/AMBP complexes such as AM/fH, byimmunoaffinity chromatography. In addition, the AM/AM binding proteincomplex can be used to screen antibodies, particularly monoclonalantibodies, that are generated as described below.

Hybridomas that produce monoclonal antibodies against the immunogeniccomponents of the invention can be produced by well-known techniques.Hybridomas can be produced by the fusion of an immortalized cell linewith a B-lymphocyte that produces the desired antibody. Alternatively,non-fusion techniques for generating immortal antibody-producing celllines are possible, and are within the purview of the present invention(see Casali et al., 1986, Science, 234:476). Immortalized cell lines aretypically transformed mammalian cells, particularly myeloma cells ofrodent, bovine, and human origin. Most frequently, rat or mouse myelomacell lines are employed as a matter of convenience and availability.

Standard procedures can be used to select hybridomas, such as HAT(hypoxanthine-aminopterin-thymidine) selection. Hybridomas that secretedesired monoclonal antibodies can be selected by assaying the cells'culture medium by standard immunoassays, such as immunoblotting, ELISA(enzyme-linked immunosorbent assay; E. Engvall et al., 1971,Immunochemistry, 8:871-4; and D. J. Reen, 1994, Methods Mol. Biol.32:461-6), RIA, or comparable assays. Antibodies can be recovered fromthe medium using standard protein purification techniques (see Tijssen,1985, Practice and Theory of Enzyme Immunoassays, Elsevier, Amsterdam).

Agonists/Antagonists of AM, AM-Binding Proteins, or Factor H

Agonists/antagonists that modulate AM activity, AM-binding protein(e.g., factor H) activity, or affect AM/AMBP (e.g., AM/fH) interactionmay be employed as therapeutics. For example, antagonists that inhibitAM or factor H activity, or block AM/fH interaction may be formulatedinto pharmaceutical compositions that are used to inhibit the growth orproliferation of cancer cells, in particular, bladder cancer, breastcancer, and glioblastoma cells. Alternatively, agonists that increase AMactivity and antagonists that decrease factor H activity or preventAM/fH interaction can be formulated into pharmaceutical compositions andused to treat microbial infection, in particular, bacterial infection.

Modulators may comprise nucleic acids, oligonucleotides; polypeptides,peptides; oligosaccharides; lipids; antibodies, or derivatives orfragments of any of the foregoing, or other organic or inorganicmolecules. Modulators can be identified using methods well-known in theart, such as, for example, by screening natural product libraries,fermentation libraries (encompassing plants and microorganisms),combinatorial libraries, compound files, and synthetic compoundlibraries for compounds that have the ability to bind to, and/or alterthe function of AM or AM-binding protein (e.g., factor H). Inparticular, synthetic compound libraries can be obtained from commercialsources (e.g., Maybridge Chemical Co. (Trevillet, Cornwall, UK);Comgenex (Princeton, N.J.); Brandon Associates (Merrimack, N.H.); andMicrosource (New Milford, Conn.). In addition, a rare chemical librarycan be obtained from Aldrich Chemical Company, Inc. (Milwaukee, Wis.).Alternatively, libraries of natural compounds in the form of bacterial,fungal, plant and animal extracts are available from, for example, PanLaboratories (Bothell, Wash.), or are readily producible. Additionally,natural and synthetically produced libraries and compounds are readilymodified through conventional chemical, physical, and biochemical means(Blondelle et al., 1996, Trends in Biotech. 14:60).

In one embodiment of the present invention, modulators may be identifiedby screening test molecules against AM or AM-binding protein (e.g.,)nucleic acid or amino acid sequences in high-throughput assays. Suchassays include without limitation genetic, biochemical, and ligandbinding assays. Several methods of automated assays have been developedto permit screening of tens of thousands of compounds in a short periodof time. These methods are particularly preferred. The use ofhigh-throughput screening assays to test for modulators is greatlyfacilitated by the availability of large amounts of purified nucleicacid or amino acids sequences, as provided by the invention.

Ligand-binding assays can be used to detect binding of test compounds toparticular sequences. The detection may involve direct measurement ofbinding. Alternatively, indirect indications of binding may involvestabilization of protein structure or disruption of a biologicalfunction. Non-limiting examples of useful ligand-binding assays aredetailed below.

A useful method for the detection and isolation of binding proteins orpeptides is the Biomolecular Interaction Assay (BIAcore) system(Pharmacia Biosensor, LKB Pharmacia, Sweden). The BIAcore system usesaffinity purified anti-GST antibodies to immobilize GST-fusion proteinsonto a sensor chip. A protein or peptide of interest is coated onto achip and test compounds are passed over the chip. Binding is detected bya change in the surface plasmon resonance, which is an opticalphenomenon that detects changes in refractive indices.

Alternatively, binding proteins can be identified by scintillationproximity assays (SPAs, described in U.S. Pat. No. 4,568,649). In amodified version of this assay, a tagged protein is attached to SPAbeads, and test compounds are added. The tagged protein is thensubjected to mild denaturing conditions (such as, e.g., heat, exposureto SDS, etc.) and a purified labeled chaperonin is added. If a testcompound has bound to a tagged protein, the labeled chaperonin will notbind; conversely, if no test compound has bound, the chaperonin willbind.

In another approach, binding proteins or peptides can be identifiedusing the binding assay described in Fodor et al., 1991, Science251:767-773). Binding proteins can also be identified by in vitromitochondrial-targeting assays (MTAs, based on Hurt et al., 1985, EMBOJ. 4:2061-2068; Eilers and Schatz, Nature, 1986, 322:228-231). Inaccordance with MTAs, expression vectors are constructed to comprise acoding sequence for a polypeptide or peptide fused with a codingsequence for a mitochondrial localization signal. The resulting fusionproteins are produced and tested for importation into isolatedmitochondria in the presence or absence of a test compound. It ispredicted that a test compound that binds to a fusion protein willinhibit mitochondrial import.

In addition, binding proteins can be identified by the yeast two-hybridsystem (Fields and Song, 1989, Nature 340:245-246; U.S. Pat. No.5,283,173). The two-hybrid system assays the reconstitution oftranscription activity through the association of a DNA-binding domainand a transcription activation domain of a transcriptional activator viaprotein-protein interactions. The yeast GAL4 transcriptional activatormay be used in this system, although other transcription factors havebeen used. In brief, the GAL4 DNA-binding domain and the transcriptionactivation domain are expressed, separately, as fusions to potentialinteracting polypeptides or peptides. If the two, coexpressed fusionproteins are targeted to the nucleus and interact, activation of areporter gene (e.g. LacZ) produces a detectable phenotype. Related invivo methods such as the three-hybrid (Licitra and Liu, 1996, Proc.Natl. Acad. Sci. USA 93:12817-12821), and reverse two-hybrid (Vidal etal., 1996, Proc. Natl. Acad. Sci. USA 93:10315-10320) systems may serveas alternative approaches.

As not all sequences are suitable for ligand binding assays, other typesof assays, e.g., cell-free biochemical assays, are also contemplated foruse. It will be appreciated by those skilled in the art that differenttypes of assays can be used to detect different types of modulators.

Diagnostics Utilizing AM-Binding Proteins

Another embodiment of the present invention is directed to in vitroscreening and diagnostic methods for detecting or monitoring thepresence of AM or AM-binding proteins, preferably factor H or relatedproteins or peptides, in biological samples, e.g., serum, plasma, orcell and tissue extracts or lysate. For use as screening and diagnosticreagents in the methods, AM, AM-binding proteins or peptides, preferablyfactor H or related proteins or peptides, can be labeled by severalestablished methods in the art. Polypeptides or peptides can beconjugated to labels using a number of different coupling agents asdescribed above, and suitable labels include, without limitation,enzyme-based, fluorescent, chemiluminescent, radioactive, or dyemolecules for use in assays that involve such labeled AM-bindingproteins. Suitable assays that amplify the signals from the target orprobe are well-known, e.g., biotin and avidin assays, and ELISAs can beused with the labeled AM-binding proteins to detect or monitor AMlevels.

To provide a basis for the diagnosis of AM-related diseases associatedwith abnormal levels of AM, a normal or standard profile for AMexpression may be established. This can be accomplished by incubatingbody fluids, tissue preparations, or cell lysates or extracts, forexample, obtained from normal subjects, either animal or human, underconditions suitable for binding with labeled AM-binding proteins orpeptides. Standard binding levels of AM to AM-binding proteins orpeptides may be quantified by comparing the values obtained from normalsubjects with those obtained from a standard or control sample in whicha known amount of substantially purified AM is used. Standard valuesobtained from normal samples can be compared with values obtained fromsamples from subjects who are symptomatic for illness. A significantdeviation between standard and test or experimental values is then usedto determine the presence and severity of a disorder or diseaseinvolving abnormal or elevated levels of AM, particularly, circulatingAM in plasma.

Following a diagnosis of a disorder or disease, and initiation of atreatment, binding assays can be repeated on a regular basis to evaluatewhether the levels of AM, e.g., plasma AM, in the patient changes, orbegins to approximate that which is observed in a normal individual. Theresults obtained from successive assays can be used to show the efficacyof treatment over a period of time, ranging from several days to months.

Additionally, AM-binding proteins or peptides may be included asreagents in AM detection or diagnostic kits. Suitable kits may includeone or more of the following components:

i) one or more AM-binding proteins or peptides, preferably factor H orrelated functional peptides thereof; the included AM-binding proteins orpeptides may be pre-labeled; alternatively, the AM-binding proteins orpeptides may be unlabelled and the ingredients for labeling may beincluded in the kit in separate containers; and

ii) reaction components such as buffers or reagents to mediate ormeasure AM-binding. The kit may also contain other suitably packagedreagents and materials needed for the binding protocol, including, forexample, solid-phase matrices, standards, and instructions forconducting the test.

A further embodiment of the present invention is directed to in vitroscreening and diagnostic methods for detecting or monitoring thepresence of the AM/fH complex in biological samples, e.g., serum,plasma, or cell and tissue extracts or lysate. For use as screening anddiagnostic reagents in the methods, antibodies that specificallyrecognize the AM/fH complex can be utilized according towell-established methods in the art. Such methods comprise the steps of:

i) contacting a sample suspected to contain altered levels of the AM/fHcomplex with an antibody specific for the complex under conditions inwhich a stable AM/fH-antibody association can form between the antibodyand AM/fH complex in the sample; and

ii) detecting any AM/fH-antibody association formed in step (i) usingany suitable means known in the art, wherein the amount of theAM/fH-antibody association detected indicates the level of AM/fH complexin the sample.

Many immunoassay formats are known in the art, and the particular formatused is determined by the desired application. An immunoassay may use,for example, a monoclonal antibody directed against a single AM/fHcomplex epitope or a combination of monoclonal antibodies directedagainst different epitopes of the AM/fH complex. Protocols may also, forexample, use solid supports, or may involve immunoprecipitation.Examples of solid supports that can be used include, without limitation,nitrocellulose (e.g., in membrane or microtiter well form), polyvinylchloride (e.g., in sheets or microtiter wells), polystyrene latex (e.g.,in beads or microtiter plates), polyvinylidene fluoride (known asIMMUNOLON™), diazotized paper, nylon membranes, activated beads, andprotein A beads. For example, Dynatech IMMUNOLON™ 1 or IMMUNOLON™ 2microtiter plates or 0.23 inch polystyrene beads (Precision PlasticBall) can be used.

Typically, immunoassays use either a labeled antibody or a labeledantigenic component (e.g., that competes with the antigen in the samplefor binding to the antibody). Suitable labels include without limitationenzyme-based, fluorescent, chemiluminescent, radioactive, or dyemolecules. Assays that amplify the signals from the probe are alsoknown, such as, for example, those that utilize biotin and avidin, andenzyme-labeled immunoassays, such as ELISA assays.

Kits suitable for antibody-based diagnostic applications typicallyinclude one or more of the following components:

(i) Anti-AM/fH complex antibodies: The antibodies may be pre-labeled;alternatively, the antibody may be unlabeled and the ingredients forlabeling may be included in the kit in separate containers, or asecondary, labeled antibody is provided; and

(ii) Reaction components: The kit may also contain other suitablypackaged reagents and materials needed for the particular immunoassayprotocol, including solid-phase matrices, if applicable, and standards.

The kits may also include instructions for conducting the test.Furthermore, in preferred embodiments, the diagnostic kits are adaptableto high-throughput and/or automated operation.

Treatments Utilizing AM-Binding Proteins

Another embodiment of the present invention embraces treatments andtherapeutic methods that comprise AM-binding proteins or peptides.Because AM-binding proteins or peptides are naturally occurring plasmacomponents, they may be administered to an individual's circulatorysystem with minimal risk of immunological complications. Pharmaceuticalcompositions can be produced and employed in treatment protocolsaccording to established methods depending on the disorder or disease tobe treated (see, for example, P. D. Mayne, 1996, Clinical Chemistry inDiagnosis and Treatment, 6^(th) ed., Oxford University Press, Oxford,England; Gilman et al., eds., 1990, Goodman and Gilman's: ThePharmacological Basis of Therapeutics, 8th ed., Pergamon Press; Avis etal., eds., 1993, Pharmaceutical Dosage Forms: Parenteral Medications,Dekker, New York; and Lieberman et al., eds., 1990, PharmaceuticalDosage Forms: Disperse Systems, Dekker, New York).

In one embodiment of the present invention, peptides derived from factorH may be used as therapeutics. Such peptides can be produced byrecombinant or synthetic techniques and then administered to tumor orcancer cells to inhibit the growth and/or proliferation of these cells.Non-limiting examples of cancer or tumor cells for use with the presentinvention include urinary bladder, urethral, renal, rectal, colon, smallintestine, gastric, esophageal, salivary gland, gallbladder, liver,breast, vaginal, endometrial, ovarian, cervical, prostate, skin, lung,or brain cancer or tumor cells. It is noted that peptide-basedtreatments would be particularly advantageous, as peptides would not beexpected to produce an undesirable immune response in the host, whichmay be observed during treatments using mouse monoclonal antibodies suchas MoAb-G6 (Miller et al., 1996, supra).

In an alternative embodiment of the present invention, antibodiesspecifically bind to the AM/fH complex may be used as therapeutics. Forexample, anti-AM/fH antibodies can be formulated into a pharmaceuticalcomposition and used to inhibit the growth or proliferation of cancercells, in particular bladder cancer, breast cancer, and brain cancercells.

It is noted that antibody-based therapeutics produced from non-humansources can cause an undesired immune response in human subjects. Tominimize this problem, chimeric antibody derivatives can be produced.Chimeric antibodies combine a non-human animal variable region with ahuman constant region. Chimeric antibodies can be constructed accordingto methods known in the art (see Morrison et al., 1985, Proc. Natl.Acad. Sci. USA 81:6851; Takeda et al., 1985, Nature 314:452; U.S. Pat.No. 4,816,567; U.S. Pat. No. 4,816,397; European Patent Publication EP171496; EP 0173494; United Kingdom Patent GB 2177096B). In addition,antibodies can be further “humanized” by any of the techniques known inthe art, (e.g., Teng et al., 1983, Proc. Natl. Acad. Sci. USA80:7308-7312; Kozbor et al., 1983, Immunology Today 4: 7279; Olsson etal., 1982, Meth. Enzymol. 92:3-16; International Patent ApplicationWO92/06193; EP 0239400). Humanized antibodies can be also be obtainedfrom commercial sources (e.g., Scotgen Limited, Middlesex, GreatBritain). Immunotherapy with a humanized antibody may result inincreased long-term effectiveness for the treatment of chronic diseasesituations or situations requiring repeated antibody treatments.

Pharmaceutical compositions may be produced as neutral or salt forms.Salts can be formed with many acids, including, but not limited to,hydrochloric, sulfuric, acetic, lactic, tartaric, malic and succinicacids. Compositions can take the form of solutions, suspensions,suppositories, tablets, pills, capsules, sustained release compounds, orpowders. Such formulations can contain 10%-95% (w/w) of the activeingredient, preferably 25%-70% (w/w). Pharmaceutical preparations andcompositions can also contain one or more physiologically acceptablecarrier(s), excipient(s), diluent(s), disintegrant(s), lubricant(s),plasticizer(s), filler(s), colorant(s), dosage vehicle(s), absorptionenhancer(s), stabilizer(s), or bacteriocide(s). The production andformulation of such compositions and preparations are carried out bymethods known and practiced in the art.

Following the preparation of pharmaceutical compositions, they may beplaced in appropriate containers and labeled for the treatment ofindicated conditions. Such labeling can include amount, frequency, andmethod of administration. Preparations may be administered systemicallyby oral or parenteral routes. Non-limiting parenteral routes ofadministration include subcutaneous, intramuscular, intraperitoneal,intravenous, transdermal, inhalation, intranasal, intra-arterial,intrathecal, enteral, sublingual, or rectal.

A therapeutically effective amount of a pharmaceutical compositioncontaining one or more AM-binding proteins or peptides is an amountsufficient to reduce, ameliorate, or eliminate a disease or disorderrelated to abnormal AM levels. An effective amount can be introduced inone administration or over repeated administrations to an individualbeing treated. Therapeutic administration can be followed byprophylactic administration, after treatment of the disease. Aprophylactically effective amount is an amount effective to preventdisease and will depend upon the specific illness and subject. Thetherapeutically effective dose may be estimated initially, for example,either in cell culture assays or in animal models, usually mice, rats,rabbits, dogs, sheep, goats, pigs, or non-human primates. The animalmodel may also be used to determine the maximum tolerated dose andappropriate route of administration. Such information can then be usedto determine useful doses and routes for administration in humans.

As an alternative approach, host cells can be genetically engineered tocarry a nucleic acid encoding an AM-binding protein, or peptide fragmentderived therefrom, and then introduced into a subject in need ofmodulation or reduction of AM levels. Following expression andproduction of the AM-binding protein by the cell, the so-producedAM-binding protein or peptide can act to bind AM and effect a diseasestate or disorder associated with abnormal levels of AM. Host cells maybe genetically engineered by a variety of molecular techniques andmethods known to those having skill in the art, for example,transfection, infection, or transduction. Transduction as used hereincommonly refers to cells that have been genetically engineered tocontain a foreign or heterologous gene via the introduction of a viralor non-viral vector into the cells. Transfection more commonly refers tocells that have been genetically engineered to contain a foreign geneharbored in a plasmid, or non-viral vector. Host cells can betransfected or transduced by different vectors and thus can serve asgene delivery vehicles to transfer the expressed products into muscle.

Although viral vectors are preferred for gene transfer therapies, cellscan be genetically engineered to contain nucleic acid sequences encodingthe desired gene product(s) by various methods known in the art. Forexample, cells can be genetically engineered by fusion, transfection,lipofection mediated by the use of liposomes, electroporation,precipitation with DEAE-Dextran or calcium phosphate, particlebombardment (biolistics) with nucleic acid-coated particles (e.g., goldparticles), microinjection, or genetically engineered microorganisms (K.Yazawa et al, 2000, Cancer Gene Ther. 7:269-274). Vectors forintroducing heterologous (i.e., foreign) nucleic acid (DNA or RNA) intomuscle cells for the expression of active bioactive products are wellknown in the art. Such vectors possess a promoter sequence, preferably apromoter that is cell-specific and placed upstream of the sequence to beexpressed. The vectors may also contain, optionally, one or moreexpressible marker genes for expression as an indication of successfultransfection and expression of the nucleic acid sequences contained inthe vector. In addition, vectors can be optimized to minimize undesiredimmunogenicity and maximize long-term expression of the desired geneproduct(s) (see Nabel, 1999, Proc. Natl. Acad. Sci. USA 96:324-326).Moreover, vectors can be chosen based on cell-type that is targeted fortreatment. For example, vectors for the treatment of tumor or cancercells have been described (P. L. Hallenbeck et al., 1999, Hum. GeneTher. 10:1721-1733; T. Shibata et al., 2000, Gene Ther. 7:493-498; M.Puhlmann et al., 2000, Cancer Gene Ther. 7:66-73; N. Krauzewicz et al.,2000, Adv. Exp. Med. Biol. 465:73-82).

Illustrative examples of vehicles or vector constructs for transfectionor infection of the host cells include replication-defective viralvectors, DNA virus or RNA virus (retrovirus) vectors, such asadenovirus, herpes simplex virus and adeno-associated viral vectors.Adeno-associated virus vectors are single stranded and allow theefficient delivery of multiple copies of nucleic acid to the cell'snucleus. Preferred are adenovirus vectors. The vectors will normally besubstantially free of any prokaryotic DNA and may comprise a number ofdifferent functional nucleic acid sequences. An example of suchfunctional sequences may be a DNA region comprising transcriptional andtranslational initiation and termination regulatory sequences, includingpromoters (e.g., strong promoters, inducible promoters, and the like)and enhancers which are active in the host cells. Also included as partof the functional sequences is an open reading frame (polynucleotidesequence) encoding a protein of interest. Flanking sequences may also beincluded for site-directed integration. In some situations, the5′-flanking sequence will allow homologous recombination, thus changingthe nature of the transcriptional initiation region, so as to providefor inducible or noninducible transcription to increase or decrease thelevel of transcription, as an example.

In general, the encoded and expressed AM-binding protein may beintracellular, i.e., retained in the cytoplasm, nucleus, or an organelleof a cell, or may be secreted by the cell. For secretion, the naturalsignal sequence present in the AM-binding protein may be retained.Alternately, an AM-binding protein or a fragment derived therefrom canbe fused to a signal sequence to allow secretion of the fusion protein.

As previously mentioned, a marker may be present for selection of cellscontaining the vector construct. The marker may be an inducible ornon-inducible gene and will generally allow for positive selection underinduction, or without induction, respectively. Examples of marker genesinclude neomycin, dihydrofolate reductase, glutamine synthetase, and thelike. The vector employed will generally also include an origin ofreplication and other genes that are necessary for replication in thehost cells, as routinely employed by those having skill in the art. Asan example, the replication system comprising the origin of replicationand any proteins associated with replication encoded by a particularvirus may be included as part of the construct. The replication systemmust be selected so that the genes encoding products necessary forreplication do not ultimately transform the cells. Such replicationsystems are represented by replication-defective adenovirus (see G.Acsadi et al., 1994, Hum. Mol. Genet. 3:579-584) and by Epstein-Barrvirus. Examples of replication defective vectors, particularly,retroviral vectors that are replication defective, are BAG, (see Priceet al., 1987, Proc. Natl. Acad. Sci. USA, 84:156; Sanes et al., 1986,EMBO J., 5:3133). It will be understood that the final construct maycontain one or more genes of interest, for example, one or more genesencoding bioactive AM-binding proteins. In addition, cDNA, syntheticallyproduced DNA, PCR amplified, or chromosomal DNA may be employedutilizing methods and protocols known and practiced by those havingskill in the art.

According to one approach for gene therapy, a vector encoding anAM-binding protein is directly injected into the recipient cells (invivo gene therapy). Alternatively, cells from the intended recipientsare explanted, genetically modified to encode an AM-binding protein, andreimplanted into the donor (ex vivo gene therapy). An ex vivo approachprovides the advantage of efficient viral gene transfer, which issuperior to in vivo gene transfer approaches. In accordance with ex vivogene therapy, the host cells are first infected with engineered viralvectors directing the expression of at least one AM-binding protein,suspended in a physiologically acceptable carrier or excipient such assaline or phosphate buffered saline, and the like, and then administeredto the host. The desired AM-binding protein is expressed by the injectedcells, which thus introduce the AM-binding protein into the host. Theintroduced AM-binding protein can thereby be utilized to treat orameliorate a disorder that is related to altered circulating levels ofAM.

EXAMPLES

The examples as described herein are intended to further illustrate thepresent invention and are not intended to limit the invention.

Example 1

Non-radioactive labeling of AM was accomplished by conjugating syntheticAM comprising amino acids 1-52 (Phoenix Pharmaceuticals, Inc.,Mountainview, Calif.) with succinimidyl esters linked to biotin (PierceChemical Co., Rockford, Ill.), fluorescein (Molecular Probes, Inc.,Eugene, Oreg.), or dinitrophenol (DNP; Molecular Probes, Inc.). Briefly,100 μg of AM (16 μM) was dissolved in 1 ml of 50 mM sodium bicarbonate,pH 8.5, and the succinimidyl ester was added to yield a final molarconcentration of 10:1 (linker:AM). The mixture was incubated with slowagitation for 1 hr at room temperature and the reaction was terminatedby the addition of 0.1 M ethanolamine followed by another incubation for1 hr. Unincorporated ligand was removed by extracting the AM usingreverse phase Sep-Pak C-18 cartridges (Waters, Milford, Mass.) andeluting the sample with acidic-isopropanol. The extract was lyophilizedand reconstituted in 1 ml of TBS (0.05 M Tris-HCl, 0.15 M NaCl), 0.1%alkali-treated casein (ATC), 0.1% Tween 20, and 0.05% Triton X-100, pH7.4. Labeled AM was stored at 4° C. for as long as 3 months withoutsignificant loss of activity.

Example 2

AM-binding proteins were identified using an in vitro screening method.Total proteins derived from human plasma (2 μl) were electrophoreticallyfractionated on 3-8% Tris-acetate gel (Novex, San Diego, Calif.) undernon-reducing conditions. For the ligand blotting experiment, theproteins were transferred to a 0.2 mm nitrocellulose membrane that wasincubated for 15 min with 1% Nonidet P-40 (NP-40). Non-specific bindingwas further blocked with a 2 hr incubation in TBS containing 0.1% ATC.Incubations with 70 nM AM labeled with biotin, fluorescein, or DNP werecarried out overnight at 4° C. in blocking buffer containing 0.1% Tween20. For biotin detection, the ligand blot was incubated with anavidin-biotin-peroxidase complex and the AEC reagent (VectorLaboratories, Inc., Burlingame, Calif.). For fluorescein and DNP, theligand blots were incubated 1 hr at room temperature with rabbitanti-fluorescein or anti-DNP IgG, respectively, (1:1000 in incubationbuffer; Molecular Probes, Inc.). Anti-rabbit antibody labeled withalkaline phosphatase (1:2000; Dako Corporation, Carpenteira, Calif.) wasadded for 0.5 hr, and the blot was developed using 4-nitro bluetetrazolium chloride/5-bromo-4-chloro-3-indolyl phosphate (NBT/BCIP) asthe color-substrate solution (Roche Molecular Biochemicals,Indianapolis, Ind.). Ligand blotting was used to detect AMBP-1, a 120 kDprotein subsequently identified as human complement factor H. FIG. 1.

Example 3

Competition of full-length AM binding to AM-binding proteins was testedby pre-incubating a membrane having plasma derived proteins boundthereto with 7 μM of unlabeled peptides; e.g., CGRP, amylin, insulin,IGF-1, PAMP, or AM truncated polypeptides (AM₁₋₁₂, AM₁₆₋₂₁, AM₂₂₋₅₂,AM₁₃₋₅₂, AM₃₄₋₅₂) for 6 hr at 4° C. Following this preincubation,labeled full-length AM was introduced and incubated overnight at 4° C.Competition studies indicated that only full-length AM was able todissociate the AM/AMBP-1 (AM/fH) complex. FIGS. 2 and 3.

Example 4

According to the present invention, a plasma-derived polypeptide thatshowed specific binding to full-length AM was determined to be factor H.Prior to the formal identification of this AM-binding protein as factorH, it was termed “AM-binding protein” or “AMBP-1” by the presentinventors. Isolated and purified AMBP-1 was found to have a molecularweight of approximately 120 kD when subjected to SDS-PAGE undernonreducing conditions.

AMBP-1 was purified to homogeneity using HPLC (FIG. 4A) followed bySDS-PAGE under non-reducing conditions (FIGS. 4B and 4C). Preparativereverse phase high performance liquid chromatography (HPLC) wasperformed using a Delta Pak C18-300 Å column (30 mm×30 cm, Waters,Tokyo, Japan) and the “System Gold” modular system (Beckman InstrumentsInc., Fullerton, Calif.). Two and one-half milliliters of human plasmawere mixed with an equal volume of 10% acetonitrile with 0.2%trifluoroacetic acid, processed through a 0.2 μm filter and loaded ontothe column. After 5 min with 0.1% trifluoroacetic acid in 5%acetonitrile, the column was eluted with a linear gradient ofacetonitrile containing 0.075% trifluoroacetic acid from 5% to 60% at aflow rate of 12 ml/min over 60 min. Each fraction (12 ml) was collected,freeze-dried and dissolved in 0.3 ml of TBS 0.1% Tween 20. Fractionswere separated by SDS-PAGE and then stained with Coomassie Blue (FIG.4B) or tested for the presence of AMBP-1 using the non-radioactiveligand blotting technique (FIG. 4C).

AMBP-1 was identified in fractions number 48-51, and was found to beconcentrated in fractions number 48-49 (FIGS. 4B and 4C). Fractionnumber 49 was electophoresed by preparative SDS-PAGE and electroblottedto PVDF. The AMBP-1 band was identified by Coomassie brilliant blue R™staining, excised, and used for amino acid analysis and amino acidsequence analysis.

Example 5

Amino acid analysis was performed by The Protein/DNA Technology Centerat the Rockefeller University, New York. HPLC (NovaPak C18 30 cm-column)with the Waters PicoTag Workstation and a two pump gradient system(model 510) equipped with a model 490 UV multiwavelength detector wereused as previously described (F. Gharandaghi et al., 1992, in Techniquesin Protein Chemistry III pp. Academic Press, Inc., San Diego, Calif., pp249-260). The results of the AMBP-1 amino acid analysis are shown belowin Table 1 in which % AMBP-1 and % fH are compared.

TABLE 1 Amino acid composition of AMBP-1 and factor H % of total aminoacid composition^(a) AMBP-1 fH^(c) Asx^(b) 12.7 9.4 Glx^(b) 13.2 12.2Ser 8.1 8.2 Gly 8.3 8.5 His 2.6 2.5 Arg 4.4 4.9 Thr 6.4 6.6 Ala 3.4 3.3Pro 7.8 8.0 Tyr 5.8 6.1 Val 6.4 5.5 Met 0.9 1.7 Ile 5.8 5.9 Leu 5.0 5.0Phe 2.8 2.7 Lys 6.4 7.0 ^(a)Since tryptophan and cysteine are destroyedby the hydrolysis of the protein in 6 M HCl, the calculated compositionof factor H corresponds to the 18 amino acids recovered. ^(b)Thecombined values for asparagine and aspartic acid, and glutamine andglutamic acid are expressed as Asx and Glx, respectively. ^(c)The aminoacid composition of factor H was obtained from the protein sequencedatabase SWISS-PROT (accession number: P08603).

Although the percentage of methionine determined for AMBP-1 was aboutone-half of the percentage of methionine predicted for factor H, therecovery of methionine from the control protein (bovine serum albumin)was also about half of the expected value. The amino acid compositionprofile was used to search a sequence database. This search indicatedthat the amino acid composition profile shared the highest degree ofsimilarity to human complement factor H.

The N-terminal sequence analysis was performed by the BiotechnologyResource Laboratory, Protein Sequencing and Peptide Synthesis Facility,Medical University of South Carolina, Charleston, S.C. The sample wassubjected to automated Edman degradation using a PE Biosystems Procise494 Protein Sequencer and a PE Biosystems cLC Microblotter 173, usingstandard cycles and reagents (P. Edman and G. Begg, 1967, Eur J.Biochem. 1:80-91; M. W. Hunkapiller et al., 1983 Methods Enzymol.91:399-413).

The Edman degradation results for AMBP-1 were analyzed using the ExPASyMolecular Biology Server protein database. This analysis indicated thatthe AMBP-1 amino acid sequence showed an 80% homology match with humancomplement factor H. Secondary amino acids were attributed to autolyticcleavage of the polypeptide. The sequence of the 15 amino acidN-terminus of AMBP-1 was identical to the N-terminus of factor H withthe exception of the threonine in position 12.

For Mass Spectrometry analysis, AMBP-1 was run on a SDS-PAGE gel underreducing conditions (5% β-mercaptoethanol). The gel was stained withCoomassie Blue and the AMBP-1 band was excised. In-gel protein digestionand peptide extraction were performed as previously described (J.Rosenfeld et al., 1992, Anal. Biochem. 203:173-179). One-tenth of theextracted protein digest was analyzed by MALDI-TOF on a PerSeptiveVoyager-DE STR (PE Biosystems, Foster City, Calif.) prior to LC/MS. Theinstrument was operated in reflector mode with the accelerating voltageset to 20000, the laser energy to 2350, the guide wire voltage to 0.05%,and the grid voltage to 95%. The mirror ratio was set to 1:110.

The remainder of the extracted protein digest was injected onto a0.3×100 mm, 5 μm BetaBasic C18 column (Keystone Scientific, Bellafonte,Pa.) which had been equilibrated with 10% buffer B in buffer A (bufferA: water with 0.1% formic acid; buffer B: acetonitrile with 10%1-propanol and 0.1% formic acid). Peptide elution was carried out usinga linear gradient progressing from 10% to 60% buffer B over 60 min(Shimadzu Sci. LC10AD/VP pumps and LC10A controller). The elutingpeptides were detected by a Finnigan LCQ Mass Spectrometer (ThermoQuest,Finnigan MAT Division, Piscataway, N.J.). Peptide sequence data wasobtained from the eluting peptides by MS/MS on those ions exceeding apreset threshold of 5×10⁴ ions. The operating parameters were asfollows: sheath gas flow set to 32, auxiliary gas flow set to 1, sprayvoltage set to 4.5 kV, capillary temperature set to 200° C., capillaryvoltage set to 8.0 volts, and tube lens offset set to −20 volts.

Example 6

The isolated AM-binding plasma protein termed AMBP-1 was compared withfactor H, based on apparent molecular weight, glycosylation, AM-binding,and recognition by anti-factor H antibodies.

Human factor H had been characterized as a glycoprotein having acalculated molecular weight of approximately 150 kD when run underreducing conditions (in the presence of 5% 2-mercaptoethanol) (R. B. Simet al., 1982, Biochem. J. 205: 285-93; P. F. Zipfel et al., 1999, Mol.Immunol. 36:241-8). It was demonstrated that AMBP-1 was glycosylatedusing the GelCode® Glycoprotein Staining Kit (Pierce Chemical Co.), andthat AMBP-1 migrated at a molecular weight of approximately 150 kD underreducing conditions. FIG. 5A.

Additionally, ¹²⁵I-labeled AM (Phoenix Pharmaceuticals, Inc.) exhibitedhigh-affinity binding to immobilized commercially produced factor H(10⁻⁸ M to 10⁻⁹ M) (FIG. 5C), and Western blot analysis indicated thatcommercially produced antibodies to factor H (Quidel Corporation, SanDiego, Calif.) recognized plasma-purified AMBP-1 (FIG. 5D). For Westernblot analysis, proteins were electrophoretically separated on a 3-8%Tris-acetate (for factor H) or a 4-12% Bis-Tris gel (for AM) undernon-reducing conditions, transferred to a 0.2 μm nitrocellulosemembrane, and blocked with 5% non-fat dry milk in PBS. Following theblocking step, the membrane was incubated with 1:2000 anti-factor Hrabbit antibody (Quidel, San Diego, Calif.) or 1:4000 anti-AM rabbitantibody (Martinez et al., 1996, supra), and developed using theECL+Plus Western Blot Detection System (Amersham Pharmacia Biotech,Piscataway, N.J.).

Example 7

To analyze the AM/fH interaction, the purified AMBP-1 (factor H)fraction (#48) was analyzed using the non-radioactive ligand-blottingassay (Example 1). After incubation with fluorescein-labeled AM, themembrane was incubated under different conditions, including PBS; PBS pH11.5; PBS pH 2.5; 4M NaCl; 4M NaCl pH 11.5; NaCl pH 2.5; 1% SDS; 3MUrea; 3M Guanidine-HCl; 3M NaSCN; 50% ethylene glycol pH 11.5; 50%ethylene glycol; 1% β-mercaptoethanol. The assay was then developed asdescribed (Example 1). FIG. 6A.

Alternatively, the AM/fH interaction was analyzed using a multi-wellassay. In accordance with this assay, a 96-well polyvinylchloride (PVC)plate was coated with factor H (5 ng/well, Sigma, St. Louis, Mo.). Theplate was blocked with a solution containing TBS, 0.1% ATC, and 0.1%Tween 20, and then incubated with fluorescein-labeled AM (50 nM) for 2hr. Prior to the development of the assay, the wells were incubated forvarious time periods with PBS or 3M NaSCN pH 7.4. Following this, theplate was washed and incubated with anti-fluorescein polyclonal antibody(1:1000, Molecular Probes) and ¹²⁵I-Protein A (Amersham PharmaciaBiotech). Radioactivity was determined using a gamma counter. FIG. 6B.

Example 8

To determine factor H and AM distribution following C18 extraction, 1 mlof human plasma was processed through a Sep Pak C18 cartridge. The boundand unbound fractions were tested for the presence of factor H byWestern blot analysis (FIG. 7A). Alternatively, bound and unboundfractions were tested for the presence of AM by immunoprecipitation ofAM followed by Western blot analysis (FIG. 7B). Immunoprecipitation ofAM was performed as follows: a 3 ml sample was incubated for 1 hr at 4°C. with 1 ml of Protein A-agarose (Life Technologies, Rockville, Md.)containing 1 μM final concentration of each of the following proteaseinhibitors: Pefabloc (Centerchem Inc., Stamford, Conn.), Bestatin, andPhosphoramidon (Sigma). The sample was then centrifuged and thesupernatant was removed to another tube. The supernatant was incubatedwith 80 μl of rabbit anti-AM antibodies (Martinez et al., 1996, supra)or rabbit preimmune serum for 1 hr at 4° C. The antibody mixture wasincubated with 80 μl of Protein A-agarose for 30 min. Following this,the immunoprecipitate was collected by centrifugation and the pellet wasextensively washed with TBS with 0.1% Triton X-100. The pellet was thenresuspended in 100 μl of LDS sample buffer (Novex) and boiled before theWestern blot analysis.

For the standard RIA protocol, plasma extraction was performed usingreverse-phase Sep-Pak C18 cartridges (Waters) as previously reported (L.K. Lewis et al., 1998, Clin. Chem. 44: 571-577; A. Martinez et al.,1999, Peptides 20:1471-1478). Briefly, cartridges were activated with80% methanol and washed with 0.9% NaCl. Plasma samples were mixed withan equal volume of phosphate buffer saline containing 0.1% ATC and 0.1%Triton X-100, pH 7.4. Samples were applied to the columns and, afterwashing twice with 0.9% NaCl, AM was eluted with 80% isopropanolcontaining 125 mM HCl. Extracts were freeze-dried to remove the organicsolvent. Concentrations of AM in the extracts were measured byradioimmunoassay as previously described (Martinez et al., 1999, supra).

For the NaSCN-modified RIA protocol, 1 ml of plasma was pre-incubatedwith an equal volume of 6M NaSCN in PBS with 0.1% ATC and 0.1% TritonX-100 pH 7.4 for 10 min at room temperature. Following this, plasma wasextracted through the C18 cartridges and AM levels were quantified. TheAM levels measured using NaSCN-modified RIA were twofold higher thanthose obtained with the standard RIA. Mean and standard deviation valuesof the three donors were 23.0±4.8 pg/ml (standard RIA) 54.3±8.6 pg/ml(NaSCN-modified RIA). Identical results were obtained using a longerNaSCN pre-incubation step (16 hr at 4° C.). Using the NaSCN-modifiedRIA, recovery of unlabeled AM added to human plasma (200 pg) was93.9±18.7% (n=3), whereas recovery of ¹²⁵I-AM was 82.7%±4.4% (n=6). Theparallel trajectory of the competitive binding curves indicated that theincrease in AM levels detected following NaSCN treatment was notattributable to an artifact. FIG. 8.

Example 9

For the cAMP assay, Rat-2 fibroblasts were grown in RPMI 1640 containing10% fetal bovine serum (Life Technologies). Cells were seeded into24-well plates at 2×10⁵ cells/well and incubated for 48 hr at 37° C. in5% CO₂. Cells were preincubated in TIS medium (RPMI 1640 plus 10 μg/mltransferrin, 10 μg/ml insulin and 50 nM sodium selenite) for 15 min.Following this, cells were treated for 5 min with AM (Bachem, King ofPrussia, Pa.) and/or factor H (Sigma) in 250 μl of TIS medium containing1% BSA, 1 mg/ml bacitracin and 100 μM isobutylmethylxanthine. Thereaction was terminated by adding an equal volume of ice-cold ethanol.Cyclic AMP was measured using the Biotrac cAMP RIA (Amersham PharmaciaBiotech). FIG. 9A.

Antimicrobial activity was measured using E. coli cells (ATCC 35218,Gaithersburg, Md.) and a radial diffusion assay as previously described(R. I. Lehrer et al., 1991, J. Immunol. Methods 137:167-173). Briefly,bacteria were incorporated into a thin underlay gel that contained 1%agarose, 2 mM HEPES pH 7.2, and 0.3 mg/ml of trypticase soy brothpowder. After polymerization of the gel, small wells (10 μl capacity)were carved in the agar. Test substances were added and allowed todiffuse for 3 hr at 37° C. A 10 ml overlay gel composed of 1% agaroseand 6% trypticase soy broth powder was poured on top of the previous geland the plates were incubated for 16 hr at 37° C. The diameters of theinhibition halos were measured to the nearest 0.1 mm and, aftersubtracting the diameter of the well, were expressed on inhibition units(10 units=1 mm). The minimal inhibitory concentration (MIC) wasestimated by performing a linear regression and determining thex-intercepts. FIG. 9B.

For statistical calculations, MIC values were analyzed by the Student'st test, cAMP values were analyzed with a one-way analysis of variance(ANOVA) and the Tukey's test, and P<0.05 was considered significant.

To measure the cofactor activity of factor H, C3b (28 pmols) wasincubated with factor I (0.16 pmols) and factor H (0.16 pmols) in thepresence or absence of AM and related peptides for 24 hr at 37° C. in afinal volume of 50 μl of PBS. Samples were fractionated by SDS-PAGEusing 4-12% Tris-Bis gels (Novex) under reducing conditions, and stainedwith Coomassie Blue. C3b and factor I were purchased from AdvancedResearch Technologies (San Diego, Calif.). FIGS. 10A and 10B.

Example 10

Northern blot analysis was used to determine the expression of factor H(4.3 kb) and FHL-1 (1.8 kb) message in various human tumor cell lines. A³²P labeled 854 by PCR product was used as a probe to detect Factor Hand FHL-1 mRNA in the same Northern blot. The sequence information forfactor H and FHL-1 was obtained from GenBank Accession Nos. Y00716(factor H) and X07523 (FHL-1). To obtain the PCR product/probe, PCR wasperformed of using a sense primer corresponding to positions 555-576 offactor H (5′-CAATGGAACCAGATCGGGATTA (SEQ ID NO:1)) and the antisenseprimer corresponding to positions 1378-1408 of factor H(5′-GACACGGATGCATCTGGGAGTA (SEQ ID NO:2)). Total RNA from human liverwas reverse transcribed to cDNA and used as template. The northern gelwas loaded with 15 μg total RNA per well (carcinoma samples), or 5 μgtotal RNA per well (normal skin sample). To confirm equivalent amountsof total RNA loaded in each well, the gel was stained with ethidiumbromide and illuminated with UV. FIG. 11.

Example 11

For Immunohistochemical analysis, 6 male albino Wistar rats wereeuthanized with CO₂, and perfused with the fixative (4%paraformaldehyde) through a heart canula. The pancreas from each rat wasextracted and immersed in the same fixative for an additional period of5 h. After dehydration, the tissues were embedded in paraffin andsectioned according to routine procedures.

Two commercially available polyclonal antibodies against human factor Hwere used in conjunction with an avidin-biotinylated peroxidasedetection kit (Dakopatts, Glostrup, Denmark). The antibodies were goatanti human factor H (Quidel, San Diego, Calif.) and rabbit anti humanfactor H (Serotec, Raleigh, N.C.). To ensure the specificity of thesignal, liquid-phase and solid-phase absorption controls were performedwith purified human factor H (Sigma, St. Louis, Mich.). For liquid-phaseabsorptions, 10 nmols of factor H were added per ml of optimally dilutedantibody for 2 hr at room temperature before incubating the tissuesections. For solid-phase absorptions, factor H was linked to UltralinkBiosupport Medium (Pierce, Rockford, Ill.), the optimally dilutedantibody was exposed to it for 2 hr at room temperature, and the immunecomplexes removed by centrifugation. FIGS. 12A-12C.

Anti-factor H antibodies were then purified by affinity chromatographycolumn containing solid-phased factor H. Briefly, 1 mg of factor H wascovalently coupled to 250 mg UltraLink Biosupport Medium (Pierce)following manufacturer's instructions. Rabbit anti-factor H serum (250μl) was incubated with the resin for 16 hr in 5 ml of PBS at 4° C.Following this, the resin was packed in a column and washed intensivelywith PBS. The bound antibody was eluted with 0.1 M citric acid, pH 3.3.The eluate was neutralized with 1 M sodium phosphate pH 8.0, and thebuffer changed to PBS by ultracentrifugation in Centricon 50 columns(Amicon, Millipore Corporation, Bedford, Mass.). Solid-phase absorptionof this affinity-purified antibody resulted in a successful quenching ofthe staining. FIG. 12D.

Example 12

Triple immunofluorescence labeling and confocal microscopy was performedas follows. Non-specific binding was blocked with donkey normal serum(Jackson Immunoresearch Laboratories, West Grove, Pa.). Paraffinsections were incubated in a mixture of three primary antibodies,including: i) Guinea-pig anti bovine insulin antibodies (1:2,000)(Jackson Immunoreasearch Labs.); ii) affinity purified rabbit anti humanfactor H antibodies (1:200) described above; and iii) one of thefollowing monoclonal antibodies: anti-somatostatin antibodies(1:10,000), anti-glucagon antibodies (1:1,000), or anti-rat pancreaticpolypeptide antibodies (1:500) (all obtained from CURE (UCLA, CA)).

Following overnight incubation at 4° C., the sections were incubated for1 hr with a mixture of secondary antibodies, including Cy5-conjugateddonkey anti-Guinea-pig antibodies (Jackson Immunoresearch Laboratories),Bodipy-conjugated anti-mouse antibodies (Molecular Probes, Eugene,Oreg.), and biotinylated goat anti-rabbit (Dakopatts), all at a finalconcentration of 1:200. The sections were then incubated with lissaminerhodamine streptavidin (1:200) (Jackson Immunoresearch Laboratories) for1 h. After extensive washing, the slides were mounted in SlowFadesolution (Molecular Probes) and observed with a Zeiss Laser Scanningmicroscope 510, equipped with four lasers. FIGS. 13A-13L.

Example 13

For immunoelectron micrographic studies, 4 male albino Wistar rats wereeuthanized and pancreatic-extraction was performed as previouslydescribed. Small fragments of each pancreas were fixed in 1%glutaraldehyde plus 2% paraformaldehyde in 0.1 M cacodylate buffer, pH7.2 at 4° C. for 2 h. The fragments were then dehydrated, and embeddedin the epoxy resin, TAAB-812 (TAAB Labs. England). Ultrathin sections(60-80 nm) were placed on nickel grids, etched for 5 min in 3% H₂O₂, andsubjected to double immunogold staining (J. Lopez et al., 1999, Gen.Comp. Endocrinol. 115:309-322). Briefly, the sections were incubated ina mixture of both primary antibodies (anti-insulin and anti-factor H) at4° C. overnight. On the following day, the sections were incubated withsecondary antibodies conjugated to gold particles (E-Y LaboratoriesInc., San Mateo, Calif.). The large gold particles (20 nm in diameter)localized the anti-insulin antibody, while the small gold particles (10nm) localized the anti-factor H antibody. The grids were washedextensively and stained with 5% aqueous uranyl acetate for 15 min, andwith lead hydroxide for 7 min. The stained sections were analyzed usinga JEOL-1010 electron microscope. FIGS. 14A-14C.

Example 14

The expression of complement factor H in the pancreas was confirmed byRT-PCR analysis. Primers were designed using the sequence of the mousegene (GenBank accession number M12660): sense primer (1877-1896)5′-TTGGAATTCTCCTGCCATTC-3′ (SEQ ID NO:3) and antisense primer(2644-2663) 5′-ACCTTCCATCTTTGCACACC-3′ (SEQ ID NO:4). Total RNA wasprepared from the liver and pancreas of two Balb/c mice, and reversetranscription was performed using the SuperScript PreamplificationSystem (Life Technologies, Gaithersburg, Md.). PCR amplified wasperformed with eLONGase enzyme mixture (Life Technologies) for 35cycles, with an annealing temperature of 57° C. The PCR products werecloned into pCR-Blunt II-TOPO (Invitrogen, Carlsbad, Calif.) andsequenced by Lark Technologies (Houston, Tex.). RT-PCR results wereconfirmed by Southern blot analysis. FIGS. 15A and 15B.

Example 15

Pancreatic islets were isolated from 12 rats as previously described (A.Martinez et al., 2000, Endocrinology 141:406-411). Briefly, the heart ofeach rat was perfused with Hank's balanced salt solution (Sigma) toremove blood from pancreatic vessels. A small canula was inserted intothe common biliary duct while the coledoco was sealed. Twenty totwenty-five milliliters of 0.4 mg/ml collagenase XI (Sigma) in Hank'ssolution was pumped through the canula until the pancreas was fullyinflated. The pancreas was removed and incubated at 37° C. for 20 min.Following this, 20 ml of ice-cold Hank's solution was added and thepancreas dissociated by vigorous vortexing. After several washes, theislets were collected and distributed into 24 well plates using adissecting microscope, with approximately 70 islets per well.

Freshly isolated islets were incubated in RPMI-1640 (Life Technologies)containing 5.6 mM glucose for 45 min at 37° C. The supernatant wasisolated for analysis and the islets incubated in RPMI-1640 containing20.6 mM glucose plus the potential secretagoges (AM and/or factor H) foranother 45 min. The medium was isolated for analysis and the islets weredissolved in ice-cold ethanol to measure cAMP production. Insulin andcAMP were measured by radioimmunoassay with commercial kits (Amersham,Arlington Heights, Ill.), according to the manufacturer's directions.FIGS. 16A and 16B.

Insulin release was expressed as the ratio between the contents in thehigh glucose medium divided by the amount in the low glucose medium toallow for variations in the number of secreting cells and/or theirsecretory efficiency. Graphs represent the mean and standard deviationof three wells per treatment. These experiments were performed threetimes with comparable results. Two-tailed Student's test was performedto determine statistical significance. P values<0.05 were consideredstatistically significant.

Example 16

Experiments were carried out utilizing radiolabeled AM as ligand.Radioligand blotting assays were performed to establish that AM-BPs werepresent in the plasma of several animal species and to further determinethe specificity of binding between AM and the plasma-derived AM-bindingprotein on a solid membrane such as nitrocellulose (see T. H. Elsasseret al., 1999, Endocrinology 140:4908-4911).

Blood sera and plasma were collected and pooled from calves (4-5 monthsold), pigs (6-7 months old), goats (2 years old), dogs (6-8 years old),mice (4-6 months old), chickens (6-8 weeks old), and human (adult male)and were aliquoted and stored at −20° C. until needed. Initialchromatographic determination of high molecular weight plasma proteinscapable of binding recombinant human ¹²⁵I-AM (Phoenix Pharmaceuticals,Mountain View, Calif.) was accomplished using a 0.7×30 cm column ofSephadex© G-50 superfine (Pharmacia LKB, Uppsala, Sweden) equilibratedwith 50 mM phosphate, 50 mM disodium EDTA, 135 mM NaCl, 0.1% Tween 20and 0.125% alkaline-hydrolyzed casein (AHC; 7), pH 7.2. For gelchromatography studies of solution binding of ¹²⁵I-AM to plasmaproteins, bovine plasma (0.1 or 0.3 ml) was mixed with 50,000 cpm of¹²⁵I-AM, incubated at 4° C. overnight and applied to the column withphosphate buffered saline in a final volume of 0.5 ml. One milliliterfractions were collected using gravity flow and the radioactivity wasquantified.

Further detection and characterization of AM-BPs were performed usingradioligand blotting procedures similar to those described for IGFbinding proteins in plasma (P. Hossenlopp et al., 1986, Anal. Biochem.154:138-146). Briefly, plasma or serum from the ten species was diluted1:5 with water and further mixed 1:2 with SDS Tris-glycineglycerolloading buffer and incubated for 10 min at 70° C. Plasma or serumvolumes equivalent to 1.5 μl were loaded onto 10% acrylamide gels undernon-reducing conditions. Proteins were separated at 115 v for 0.5 hr andtransferred to 0.2 μm nitrocellulose using a semi-moist transfer(Bio-Rad Hercules, Calif.) at 18 v for 42 min. Molecular weight markers(29 kD, 43 kD, 66 kD, 78 kD, and 116 kD) were added to complementarylanes on each gel to assess the relative sizes of the resolved proteins.

Nitrocellulose blots were incubated for 15 min with 1.5% NP-40 (Sigma,St. Louis, Mo.). Nonspecific binding was further blocked with a 4 hrincubation of the nitrocellulose in phosphate buffered saline containingeither 1% BSA (RIA Grade, SIGMA, St. Louis, Mo.) or 1% AHC. Incubationswith radiolabeled recombinant human ¹²⁵I-AM were performed overnight atroom temperature with agitation, with 80,000 CPM ¹²⁵I-hAM per 5 mlprotein blocking matrix. The next morning, the nitrocellulose was washed10 min with 0.2% NP-40, and further washed 4 times for 15 min per washwith phosphate buffered saline. Following air drying, the nitrocellulosewas loaded into a phosphoimaging cassette (Molecular Dynamics,Sunnyvale, Calif.) overnight for analysis of resolved band images.Additional characterization of the banding patterns was accomplished byautoradiography of the blots on Kodak AR-5 film with a 4-day exposure at−80° C. Removal of apparent binding proteins from plasma wasaccomplished using the C-18 reverse-phase Sep-Pak® RIA preparatorytechnique (A. Martinez et al., 1997, Endocrinology 138:5597-5604). FIG.17.

Competitive displacement of ¹²⁵I-AM from separated proteins onnitrocellulose ligand blot strips was performed to assess thespecificity of the AM binding to the AM-binding protein. Blot stripswere incubated in buffer containing 0.1% AHC, ¹²⁵I-AM, andconcentrations of recombinant human AM ranging from 10⁻¹⁰ to 10⁻⁶ M. Theintensity of the band images was resolved by phosphoimagingdensitometry. Additional aspects of AM specificity for the bindingprotein(s) were assessed by co-incubating ¹²⁵I-AM overnight withauthentic AM₁₋₅₂ (10⁻⁶M) or AM₁₋₁₂, AM₁₃₋₅₂₁ AM₃₄₋₅₂ peptide fragments,or amylin, CGRP or insulin used at 10⁻⁵ M. The results showed a linearcompetitive displacement of ¹²⁵I-AM from the AMBPs in the presence ofincreasing concentrations of non-labeled synthetic AM (Elsasser et al.,1999, supra).

Example 17

A comparison of ¹²⁵I-AM blot binding patterns in bovine plasmas fromhealthy and parasitized calves was used to determine whether plasmaAM-BP content was affected by the health status of a subject (Elsasseret al., 1999, supra). Nitrocellulose transfer blots of plasma proteinsfrom normal healthy 4 month old calves (n=3) and calves infected with avascular endothelial-resident parasite (Sarcocystis cruzi), (n=4), wereprobed with ¹²⁵I-AM. Plasma from infected calves was obtained on day 30post oral inoculation (250,000 oocysts) at the peak of expression ofclinical signs of the acute phase response associated with the eruptionof schizonts from the endothelium (T. H. Elsasser et al., 1988, J.Endocrinol. 116:191-200).

Data on the effects of parasitic infection on the amount of AM-BP incalf plasma were statistically analyzed using an analysis of varianceapproach based on the general linear models procedure of SAS (SAS 1986General Linear Models Procedure: SAS for personal computers, SASInstitute, Cary, N.C.).

Autoradiograms of proteins transferred to nitrocellulose and probed withradiolabeled ¹²⁵I-hAM demonstrated that plasma from all of the speciestested contained at least one protein that bound to the AM tracer, i.e.,an AM-binding protein. This AM-BP was a high molecular weight protein ofabout 120-130 kD, more specifically, 120 kD. In plasma from the calf,goat, sheep, and to a lesser extent dog, an additional band of 140 kDwas observed.

In addition, ¹²⁵I-AM ligand blotting demonstrated that the content ofspecific AM-binding proteins was decreased by as much as 68% in plasmaof calves experiencing the acute phase response to a parasitic challenge(P<0.03). Because both healthy and parasitized calves had similar plasmaconcentrations of total proteins, albumin and globulins, the measureddecrease in AM-BPs in the parasitized calves reflects a specificresponse in this protein class to the onset of disease. FIG. 18.

Example 18

A small molecule combinatorial library can be obtained from theDevelopmental Therapeutics Program at NIH. This library provides a totalof 250,000 compounds that have a molecular weight below than M_(r) 600.The compounds are organized in 8,000 “families” with similar structuralcharacteristics. One member of each family can be assayed for binding toAM, factor H, or AM/fH. If binding is detected, the remaining familymembers can be analyzed to identify compounds with increased bindingaffinity for AM, factor H, or AM/fH. In the initial screen, 96-wellplates can be coated with AM, factor H, or AM/fH (synthetic,recombinant, or isolated), and then incubated with various testcompounds. After extensive washing, the presence of AM, factor H, orAM/fH detected with corresponding antibodies, followed by a secondaryantibody and ¹²⁵I-protein A. Following this, individual wells can bescanned with a gamma counter. Wells containing AM-, factor H- orAM/fH-binding compounds can be identified by an increase in signalcompared the negative control (no compound added).

Compounds that are identified by their binding activity can be furtheranalyzed using various bioassays. For example, compounds can be testedusing the fibroblast cell line, Rat-2, which expresses specific AMreceptors (H. A. Coppock et al., 1999, Biochem. J. 338:15-22.). To testAM-binding compounds, the cells can be incubated with AM alone (negativecontrol) or AM plus the compound. To test fH-binding compounds, thecells can be incubated with AM alone, factor H alone, AM plus factor H(negative controls), or AM plus factor H and the compound. To testAM/fH-binding compounds, the cells can be incubated with AM/fH alone(negative control) or AM/fH plus the compound. Following this, the cAMPresponse of the cells can be analyzed by radioimmunoassay as previouslydescribed (A. Martinez et al., 1997, Endocrinology 138:55977-56048; M.J. Miller et al., 1996, J. Biol. Chem. 271:23345-23351; A. Martinez etal., 1999, Peptides 20:1471-1478).

Dose-response curves can be plotted and used to identify compounds thatinhibit AM-mediated cAMP production (compared to the negativecontrol(s)). The curves can also be used to identify high-affinitycompounds. High-affinity compounds can then be used as models forsecondary combinatorial libraries that can include ˜500 compounds. Suchlibraries can be assembled from chemically modified forms of theoriginal compound. These new compounds can be tested in the same mannerdescribed above to refine the screening process and identify a potentinhibitor of AM function, factor H function, or AM/fH interaction.

All patent applications, patents, texts, and literature references citedin this specification are hereby incorporated herein by reference intheir entirety to more fully describe the state of the art to which thepresent invention pertains.

As various changes can be made in the above methods and compositionswithout departing from the scope and spirit of the invention asdescribed, it is intended that all subject matter contained in the abovedescription, shown in the accompanying drawings, or defined in theappended claims be interpreted as illustrative, and not in a limitingsense.

1. An isolated protein complex comprising adrenomedullin and factor H.2. A method of treating an adrenomedullin-related condition in a subjectcomprising administering to the subject the isolated protein complex ofclaim 1, thereby treating the adrenomedullin-related condition.
 3. Apharmaceutical composition comprising the isolated protein complex ofclaim 1, and a physiologically acceptable carrier, excipient, ordiluent.
 4. A method of treating an adrenomedullin-related condition ina subject comprising administering to the subject the pharmaceuticalcomposition of claim 3, thereby treating the adrenomedullin-relatedcondition.
 5. An antibody specifically reactive with an epitope formedby the complexation of adrenomedullin and factor H, or acomplex-specific fragment thereof.
 6. The antibody of claim 5, whereinthe antibody is a monoclonal antibody.
 7. A pharmaceutical compositioncomprising the antibody of claim 6, and a physiologically acceptablecarrier, excipient, or diluent.
 8. A method of isolatingadrenomedullin/factor H protein complexes from a biological sample,comprising: i) providing a solid support having bound thereto theantibody of claim 5; ii) contacting said support with the sample; andiii) eluting the adrenomedullin/factor H complex that binds to theantibody bound to the support.
 9. The method according to claim 8,wherein the sample is selected from the group consisting of plasma,serum, cell lysate, and tissue extract samples.
 10. A method fordetecting adrenomedullin/factor H protein complexes in a biologicalsample, comprising: i) incubating the sample with the antibody of claim5 under conditions allowing binding of the antibody to theadrenomedullin/factor H complex in the sample; and ii) determiningbinding of the antibody to the adrenomedullin/factor H complex.
 11. Themethod according to claim 10, wherein the sample is selected from thegroup consisting of plasma, serum, cell lysate, and tissue extractsamples.
 12. The method of claim 10, wherein the antibody is labeled.13. The method of claim 12, wherein the label is non-radioactive. 14.The method of claim 12, wherein the label is an enzymatic label.